/sqt/ /qtddtot/ - stupid questions thread

[Anonymous No.15853222]

Previous: >>15828045

>what is /sqt/ for?
Questions regarding maths and science. Also homework.
>where do I go for advice?
>>>/sci/scg or >>>/adv/
>where do I go for other questions and requests?
>>>/wsr/ >>>/g/sqt >>>/diy/sqt etc.
>how do I post math symbols (Latex)?
rentry.org/sci-latex-v1
>a plain google search didn't return anything, is there anything else I should try before asking the question here?
scholar.google.com
>where can I search for proofs?
proofwiki.org
>where can I look up if the question has already been asked here?
warosu.org/sci
eientei.xyz/sci
>how do I optimize an image losslessly?
trimage.org
pnggauntlet.com
>how do I find the source of an image?
images.google.com
tineye.com
saucenao.com
iqdb.org

>where can I get:
>books?
libgen.rs
annas-archive.org
stitz-zeager.com
openstax.org
activecalculus.org
>articles?
sci-hub.st
>book recs?
sites.google.com/site/scienceandmathguide
4chan-science.fandom.com/wiki//sci/_Wiki
math.ucr.edu/home/baez/physics/Administrivia/booklist.html
>online courses and lectures?
khanacademy.org
>charts?
imgur.com/a/pHfMGwE
imgur.com/a/ZZDVNk1
>tables, properties and material selection?
www.engineeringtoolbox.com
www.matweb.com
www.chemspider.com

Tips for asking questions here:
>attach an image (animal images are ideal, you can grab them from >>>/an/. Alternatively use anime from safebooru.donmai.us)
>avoid replying to yourself
>ask anonymously
>recheck the Latex before posting
>ignore shitpost replies
>avoid getting into arguments
>do not tell us where is it you came from
>do not mention how [other place] didn't answer your question so you're reposting it here
>if you need to ask for clarification fifteen times in a row, try to make the sequence easy to read through
>I'm not reading your handwriting
>I'm not flipping that sideways picture
>I'm not google translating your spanish
>don't ask to ask
>don't ask for a hint if you want a solution
>xyproblem.info

[Anonymous No.15853230]

>>15853218

[Anonymous No.15853236]

>>15853230
No, the apothem is h/3, so the distance from the vertex to the center is 2h/3
See https://en.wikipedia.org/wiki/Equilateral_triangle

[Anonymous No.15853349]

I'm starting to realize I can differentiate anything programatically.
It either follows a rule or is a special case.
Does anyone know how I could program this?
How do I program a something that creates a function?
I mean why the hell was I ever solving derivatives in school if a computer should have been doing it the whole time?
I can't be the first person to realize this, but I've never heard of a program that produces functions, never heard about that in school.
Has anyone heard of such a thing, either a program that can generate exact derivatives or one that can generate new program functions?

[Anonymous No.15853388]

>>15848622
>Is there a book about reading scientific papers
what the fuck

[Anonymous No.15853527]

How did they solve kinematics problems in the past before calculus was invented?

[Anonymous No.15853534]

What is the largest fatty acid that humans can actually digest?

[Anonymous No.15853617]

>>15853527

[Anonymous No.15853621]

What if we run out of fossil fuels?

[Anonymous No.15853636]

>straw in pepsi/coke can
>drink and stop
>cola/fizz continues to rise up and out of straw, spilling
>mountain dew, orange juice, apple juice, alcohol, etc
>doesnt happen
whats in coke and pepsi thats not in juices or even mountain dew that causes it? i thought it would be physics based like the vacuum created bringing up the fluid, but it doesnt happen with any other drinks.

i already solved the "matter cant be created" problem with the way my house produced dust and shit, is this just another example of my ability to defy the laws of physics?

[Anonymous No.15853639]

>>15853621
thats what holocausts are for

[Anonymous No.15853641]

>>15853617
And from where were those derived?

[Anonymous No.15853645]

>>15853641
eyeballing it

[Anonymous No.15853649]

>>15853636
Sounds like carbonation. CO2 in soda rises, pushing fizz out through the straw. The differential rise through the straw may be due to Bernoulli's principle.

[Anonymous No.15853653]

>>15853621
Nuclear and deep geothermal. We can synthesize fuels like gasoline and diesel from CO2, water, and air, it's just energy intensive and not presently worth it.

[Anonymous No.15853657]

>>15853649
is mountain dew not carbonated?

[Anonymous No.15853659]

>>15853639
kek
>>15853653
Well, I hope you're right.

[Anonymous No.15853672]

Anyone know where you can download the Magma Computer Algebra System?

[Anonymous No.15853675]

>>15853657
I think it's less carbonated than other sodas.

[Anonymous No.15853750]

are there some like group-like structures for ternary relations?
and a parallel of associativity, and such properties?
is there a parallel for transitivity?

[Anonymous No.15853902]

>>15853349
it's pretty easy, i did it in a few days because there aren't that many rules

>>15853672
just use sage or pirated mathematica

[Anonymous No.15853934]

>>15853902
Mathematica doesn't has the functions I want to use. Sage might be my best bet, though annoyingly I'd have to update my OS for the latest version.

[Anonymous No.15853950]

>>15853349
start by breaking down the expression into a tree.

[Anonymous No.15854125]

>no you can't hand in your homework in latex. You have to painstakingly write it by hand, because ... ugh ... these are the rules, okay?
What is their problem, /sqt/?

[Anonymous No.15854299]

How exactly do you show that the limit of 2/x+1 as x approaches -1 = infty? Is it just that since lim x+1/2 as x approaces -1 = 0 then lim 2/x+1 = +-infty

[Anonymous No.15854319]

>>15854299
The sign will be different depending on if you approach from the left or right, but to show a function approaches positive infinity, you need to show that for any [math]\varepsilon>0[/math] and [math]M>0[/math], there is a point less than [math]\varepsilon[/math] away from [math]-1[/math] such that your function is larger than [math]M[/math]. The easiest way to do that is show explicitly that it can be done for any natural number.

[Anonymous No.15854330]

>>15853934
https://wiki.archlinux.org/title/List_of_applications/Science#Scientific_or_technical_computing

[Anonymous No.15854403]

I'm really starting to hate this board, everything is shit.

[Anonymous No.15854736]

>>15853222
why is chemistry taught before physics ?

[Anonymous No.15854747]

>>15854330
The reason I wanted magma is for this package:
https://github.com/pascalmolin/hcperiods

[Anonymous No.15854763]

>>15854736
it's not. chemistry, biology and physics are all taught at the same time unless you live in some shit hole backwater country.

[Anonymous No.15854788]

>>15854763
Why should they be taught all together? Seems like an inefficiency. Imagine reading three books at the same time. BORING.

[Anonymous No.15854807]

Can a 3D object have infinite surface area within a defined volume?

[Anonymous No.15854812]

recommended books to work through for prerequisites for waves and optics? Have contest math and CS background and taking grad classes next spring (only taken high school physics so far).

[Anonymous No.15854814]

>>15854807
https://en.wikipedia.org/wiki/Gabriel%27s_horn

[Anonymous No.15854828]

>>15854763
Well america is that

[Anonymous No.15855010]

>>15854812
read through the wiki and queued up
Physics
>Taylor mechanics
>SICM supplement (looks neat)
>Griffith Electrodynamics
Calc (I've worked through calculus 2 thus far, with background linear)
> Callahan's Advanced Calculus: A Geometric View

Thoughts are appreciated

[Anonymous No.15855322]

>>15853639
Holocausts were burnt offering sacrifices where yhwh got off to the sedative effects of certain chemicals released by burning meat and fat that mimic neurorecepters

[Anonymous No.15855456]

Is it fine to assume the axis for a 2D centre of mass or moment of inertia problem for the sake of simplicity? I don't know why but not able to get these type of problems....

Can parallel axis theorem be used if I make another axis which is on centre of mass ?

[Anonymous No.15855460]

>>15855456
*Is it fine to assume the axis anywhere for the sake of simplicity?

[Anonymous No.15855462]

>find the distance between the branch of the hyperbola xy +x +y = 0, x > -1 and a line x + 2y + 1 =0
This seems simple but I have no idea how to solve it.

[Anonymous No.15855510]

>>15853902
>>15853950
Yeah but how do I make a program recognize it's own structure?
Sounds like scifi bullshit

[Anonymous No.15855517]

Just draw a pic. It's easy to see that the tangent on the hyperbola at the point closest to line must be parallel to the line.

So implicitly differentiate the equation of the hyperbola:
y + x dy/dx + 1 + dy/dx = 0
For the line dy/dx = -1/2 so plug this in:
y - x/2 + 1 - 1/2 = 0
y = (x - 1)/2
Plug this in equation of the hyperbola to get a quadratic equation for x
x(x - 1)/2 + x + (x-1)/2 = 0
with the solution
x = -1 +- sqrt(2)
Only x = sqrt(2) - 1 is on the right branch of the hyperbola.
So the closet point to the line on the hyperbola is (sqrt(2) - 1, sqrt(2)/2 - 1).
To get the point on the line just follow the point above along the normal (-1, -2) until you hit the line which is at ((3 sqrt(2) - 3)/5, (-3 sqrt(2) - 2)/10).
The distance between those points is the L^2 norm of the difference that is
2 sqrt(5) (sqrt(2) - 1)/5
https://www.desmos.com/calculator/isdtkd2eqc

[Anonymous No.15855518]

>>15855462
There are two possible situations for this kind of thing:
>there is no single place where they're closest
>there is a place where they're closest
If there is a place where they're closest (and there is in this case, just graph it), the usual trick is that the line connecting the points where they're closest is orthogonal to both curves. One of those is a line, which closes things off nicely.

[Anonymous No.15855577]

>>15855460
For finding moment of inertia

[Anonymous No.15855611]

suicide suicide suicide

[Anonymous No.15855738]

Anyone uses chat GPT to aid in their thesis writing?
There is some paragraphs that I'd like it to be rephrased and finding hard time doing it.

[Anonymous No.15855747]

is it theoretically possible for lava to be naturally green

[Barkun No.15855749]

>>15855747

[Anonymous No.15856207]

>>15855510
Unless you're writing in Lisp, you don't. You write a parser for algebraic expressions: constants, variables, +, -, *, /, ^ (or **), function calls. Any similarity between the syntax of expressions and the syntax of the language you're writing this in is coincidental.

Tip: use a parser generator (yacc/bison or whatever), not an ad-hoc bunch of if/else statements.

[Anonymous No.15856493]

>>15856207
That's fucking bullshit I hate parsing tokens
I'm just gonna see if someone already made a solution on github or something
Now I remember that I fucking hate programming

[Anonymous No.15856507]

what's with all the hype around the Casimir Effect

[Barkun No.15856515]

>>15856507
Na'oooo

[Anonymous No.15856648]

There are reports and videos of people collapsing and almost dying (sometimes dying) from just touching a little bit of fentanyl:
https://www.youtube.com/watch?v=3e9fHAZVEvU
https://www.youtube.com/watch?v=4gA61UowVHk
How are there people who actually USE fentanyl as a drug? I know people use it as a cutting agent but you if just trace amounts are so dangerous I'm struggle to see how even those folks are dropping dead every single time.

[Anonymous No.15856698]

>>15855510
>Yeah but how do I make a program recognize its own structure?
why do you need to do this? what are you trying to do?
>>15856493
if youre just looking for something to take a derivative just use simpy.

[Anonymous No.15856735]

[math]x' - 4x + y'' = t^{2} \\ x' + x + y' = 0[/math]

Please someone explain to me how do I enter this problem into this calculator

https://mathdf.com/dif/

I tried wolfram alpha but it doesn't show steps and symbolab shits itself and shows nonsense. Mathdf was the only one that was working so far please somebody.... I'll suck your dick please...

[Anonymous No.15856765]

>>15855510
>recognize it's own structure
this is not necessary
you write a math parser in a language other than math (for example python, c++, rust, go, crystal, etc.)

[Anonymous No.15856780]

>>15856698
>why do you need to do this? what are you trying to do?
Well I need it to be able to recognize the programming functions that define the mathematical function like
sin(x^2)+e^x*cos(x)+1 => f = lambda x : add(sin(pow(x, 2)), add(mult(exp(x), cos(x)), 1))
I need to create a program that can recognize these functions and apply the chain rule and write the new function in terms of the derivative.
f = lambda x : pow(x, 2)
dfdx = lambda x : mult(2, x)
The program should be able to see the power function and then return the correct derivative as a new function.
>>15856698
>just use simpy.
can simpy do this? I'm using R for my work. If don't have to make it myself then all the better.
>>15856765
I see and I guess I can use a tree to make one right?, I made one before that parsed text input for a calculator program but it didn't use special functions.

[Anonymous No.15856824]

>>15856735
First turn it into a first order system by defining
[math]z := \dot y [/math].
Then you have the system
[eqn] \dot x = -x - z \\
\dot y = z \\
\dot z = 5x + z+ t^2
[/eqn]
which can be solved with the usual variation of constants formula.
https://encyclopediaofmath.org/wiki/Variation_of_constants

[Anonymous No.15856911]

In this screenshot of a video it shows how the wave of pressure is visible that was created by the bullet exiting the gun. And it made me think why should it be visible at all?

What I do know is that the difference in pressure in the air causes light to have different speeds. And so because of the fact that light follows a law which says that it always takes the quickest path between two points along its trajectory, that causes the trajectory to bend when the speed changes. But how does that work? Why should light take that quickest path in the first place instead of just going straight through leaving the pressure wave in the air invisible?

[Anonymous No.15857121]

holy shit why is chatGPT so fucking retarded?

[Anonymous No.15857269]

>>15857121
>Give chatGPT retarded wrong problem
>Get retarded answer
Looks like it works correctly.

[Anonymous No.15857271]

>>15856911
entropy

[Anonymous No.15857303]

>>15853222
How do I prove that for every subset A of X that f(X\A) \subset Y\f(A) if and only if f is injective? I got here: [math] \exists x\in X:f(x)=y ) \land \exists a\notin A: y=f(a)\implies x=a [/math] since f is injective, but I don't get how exactly why it has to be injective.

[Anonymous No.15857334]

>>15857303
If [math]f[/math] is not injective then you can find [math]x_1, x_2 \in X[/math] with [math]f(x_1) = f(x_2)[/math]. Now consider [math]A = \{x_2\}[/math].

[math]f(x_1) \in f(X \setminus A)[/math] since [math]x_1 \in X \setminus A[/math].
But [math]f(x_1) \not \in Y \setminus f(A)[/math] since [math]f(x_1) = f(x_2) [/math] and [math]x_2 \in A[/math].
So for non-injective [math]f[/math] there exists a set [math]A[/math] with [math]f(X \setminus A) \not \subset Y \setminus f(A)[/math].

[Anonymous No.15857339]

I need this question answered by someone who is actually going to give it proper thought and not just dismiss it because it's never crossed their minds: are 2 people who communicate experiencing the communication simultaneously? As in, we all have 1 consciousness that exists at exactly 1 point in time. However, since time is relative, that 1 point in time is different for everyone for various reasons, probably the most significant of which is your perception of time. In my "now" am i actually completely alone?

[Barkun No.15857341]

>>15857339
Correct

[Anonymous No.15857343]

>>15857339
I mean you don't even need relativity, finite speed of light and sound means you're perpetually experiencing the world on a slight delay.

[Barkun No.15857345]

>>15857341
It's more your sign I read, but the symbols are there.

[Barkun No.15857347]

It can be good but error

[Anonymous No.15857357]

>>15857341
>>15857343
I think there is a Pandora's box of thought experiments that can come from this line of thinking that may not have been considered. For instance, how does this relate to free will? If someone isn't conscious when you're talking to them because they experienced that moment already, then how can you say they have free will? The assumption is that they did have free will when it happened, so the difference is meaningless but that's just an assumption. Can we test for consciousness somehow? Is there a specific wavelength for it?

[Anonymous No.15857373]

>>15857357
>Can we test for consciousness somehow?
No. We can't even define what consciousness (physically) is, so creating a test is impossible.

> Is there a specific wavelength for it?
See above.

There's nothing special about consciousness, like everything else in the universe it follows the laws of physics. The problem is that it's a really, really, really complex problem.

[Anonymous No.15857393]

Need help guys, The only thing standing in between me and my final statics exam is moment of inertia, my retarded brain can not understand how to take element of different type of objects and find moment of inertia, Parallel axis theorem and perpendicular axis theorem went over my head.. I ready theory multiple times but not able to solve problems..old help

[Anonymous No.15857522]

>>15857393
You can think of it like "angular mass," the same way mass is a measure of how hard it is to accelerate something linearly MoI is a measure of how hard it is to accelerate something rotationally. Go read about it on hyperphysics.

[Anonymous No.15857601]

>>15857339
>are 2 people who communicate experiencing the communication simultaneously?
No.
>In my "now" am i actually completely alone?
Technically in the same sense "you" are a conceptual notion of an aggregate of things the same as "simultaneity" of communication is a concept that is not strictly true "independent our perception". Doesn't really matter though since what's "really true" here has no bearing on how we interact since we don't perceive it anyway.
>>15857357
>For instance, how does this relate to free will?
"free will" is a contradictory self-refuting concept. If you merely mean "will", things we don't perceive or experience consequence of are not going to matter by definition.
>Can we test for consciousness somehow?
Depends on how you define it, and there are many different tests for different uses or definitions. As a degreed property in species some people are of the opinion that degree descends all the way down to simple cells, or even more primitive life. It depends entirely on what definition you are working with. Would you like to reference a preferred definition?

[Anonymous No.15857617]

>>15857393
>Parallel axis theorem and perpendicular axis theorem went over my head.. I ready theory multiple times but not able to solve problems
You are going to have to explain what went over your head and where you get stuck

[Anonymous No.15857627]

>>15857617
I can solve all those simple geometry type figures but when multiple body system are mentioneed like 7 sphere or one ring hanging in another, my brain shuts off

[Anonymous No.15857638]

>>15857627
that doesn't explain what went over your head nor where you get stuck. look anon i am not going to pull it out of you. If you want help you have to explain exactly what about the theorem went over your head and exactly where in some examples you lose the plot.

Seriously why do people act like this? How is anyone supposed to help with vague "my brain gives up for this entire class of problem" okay where? And what about the parallel/perp axis theorems went over your head? Where are you having trouble? I'm not going to write entire posts guessing and flailing about just because you're too lazy to even properly ask questions.

[Anonymous No.15857754]

Is the term orthonormal coordinate system synonymous to cartesian coordinates, i.e. is the cartesian coordinate system the only coordinate system where all the Lamé coefficients are 1?

[Anonymous No.15857766]

>>15857269
That was chatGPT's problem you fucking retard.
I spent like half an hour explaining to it that it's assumption is wrong and it's reasoning is not just wrong but awful.
I'm surprised at how super awesome it is at coding but it's totally super mega shit at math.

[Anonymous No.15857786]

How do you determine rank of a matrix with parameter(s)? I know that if I get the matrix into RREF I will know, but can I determine it just from REF? The thing is that often getting the matrices I am given into RREF can be challenging so I don't think I'm supposed to do it that way.

[Anonymous No.15857801]

[eqn]
x + y+z=0 \\
bx+4y+z=0 \\
6x+(b+2)y+2z = 0
[/eqn]
The only solution to this system is (ofc) [math]x=y=z=0[/math]. Could I have somehow been sure that this is the only solution without even doing the system?

[Anonymous No.15857810]

This one stumped me chemchuds.
Seems obvious that it starts with a reduction of the ketone to an alcohol. The molecular formula shows the product as having one oxygen and two carbons less, which must mean that the ether group was cleaved off somehow.
There's already a problem here, without even considering the mechanism: According to the molecular formula, there should be 16 hydrogens in the product. However, no matter what you do, the reduction + ether cleavage always result in a product that has 17 hydrogens in total.
Mechanistically, I habe no idea how you would even try to cleave the ether.

[Anonymous No.15857836]

>>15857801
Calculate the determinant. If it's non-zero then there is a unique solution.

[Anonymous No.15857839]

>>15857836
Thanks

[Anonymous No.15857957]

>>15857638
Ok sorry anon, to be precise I face problem in multiple body systems where we have to find moment of inertia, I completely understand the theorem but not able to apply it well in some critical thinking questions (maybe the questions are easy and I am retarded) for example we have a rod of length l mass y and two boxes attached to it of mass m each...find moment of inertia through axis at midpoint

Ml^2/12 is the inertia of the rod, for the two boxes what should be done ?


Same here

Seven identical circular planar disks, each of mass mband radius r are welded symmetrically. The moment of inertia of the arrangement about the axis normal to the plane and passing through the point at the centre of middle disc.


I know we have to apply perpendicular axis theorem here but how ?

Can any anon explain the solution to these type of problems here in an layman language ? And where can I find more problem like these ? My homework assignment doesn't consist of morethese type of problems already checked classical mechanics books but most of them contain problems on angular acceleration and all that


Please HELp

[Anonymous No.15858128]

>>15857766
That just shows you have zero understanding how ChatGPT works. It's just a statistical language model to predicate lexical token (word fragments). It doesn't understand anything which is why it's terrible at math. Unless a similar math question and its answer were part of its data set it will fall apart. Similarly its why its so good with code because that is just cut & pasting words.

[Anonymous No.15858182]

Is graphene still a pipe dream?

[Anonymous No.15858192]

>>15858128
Well I wanted to see if it could help me practice math. It seems to be very good at doing my programming homework and I was just testing how it was with mathematics, and the answer is awful.
I figured it wouldn't be so bad with proving mathematics, it's just reciting 2000-200 year old theorems, plus there are thousands of proofs already online.

[Anonymous No.15858195]

>>15858182
yes

[Anonymous No.15858391]

Why are batteries based on first ionizations, when the second ionization is higher energy?
Wouldn't [math]Na^{+} \rightarrow Na^{2+}[/math] batteries have like 10x the energy density?

[Anonymous No.15858527]

I'm having trouble understanding the diagram chase in https://math.stackexchange.com/a/1999115
Specifically the part where the equality of [eqn](X \times_{X/R}A) \times_A (X \times_{X/R}A)'\rightrightarrows X\xrightarrow{f}Z[/eqn] cancels to equality of[eqn](X \times_{X/R}A) \times_A (X \times_{X/R}A)'\rightrightarrows X\xrightarrow{p}X/R[/eqn].
The answer explains this by saying that
>As [math]R[/math] is defined by [math]f[/math], we find then that the morphisms [math](X \times_{X/R}A) \times_A (X \times_{X/R}A)' \rightrightarrows X[/math] factor through [math]R[/math].
but I don't see how this can be justified without assuming what you wish to prove (that [math]g[/math] can be cancelled in the factoring [math]f=g\circ p[/math]).

[Anonymous No.15858589]

A guy I know (not me) wants to show which of the two are bigger: log_6(7) or log_8(9).
My dumbass differentiated log_x(x+1) and showed it's negative for x>1 so log_6(7) is bigger but the guy isn't supposed to know calculus yet. Is there a way to do it just with log rules?

[Anonymous No.15858604]

>1 isn't considered a prime number
My background is in metaphysics, so this question hadn't crossed my path until now, but ...

Well, has any philosopher or mathematician considered that 1, being the symbol of the metaphysical unity of all discriminate substance, is comprised itself out of the subjective experience of phenomenal reality and that of its logically necessary reciprocal condition of unconsciousness? 1 is an abstract object comprised of two subjects, that of being and non-being. Every other number is merely the multiplication of that proposition. Ergo, 1 should be considered prime because 2 is considered prime.

Now, mathchads, explain how I'm retarded.

[Anonymous No.15858651]

>>15858589
Use change of base

[Anonymous No.15858677]

>>15858651
Can you elaborate? No base I change to leads to a nice simplification that doesn't involve pulling a calculator to evaluate something which I could have done with the original question if it were allowed.

[Anonymous No.15858690]

>>15858677
nta
[math]\log_{b}x={\frac{\log_{k}x}{\log _{k}b}}[/math]
Use change of base. The resulting fraction makes it so fucking obvious dude.

[Anonymous No.15858693]

>>15858690
not anyone involved here, but how is it self-evident that [math]\frac { \log_8 (7) } { \log_8 (6) } > \log_8(9)[/math]?

[Anonymous No.15858695]

>>15858677
NTA but you can rewrite log_x(x+1) as 1+log(1+1/x)/log(x), then argue that it's strictly decreasing over your desired interval from the usual monotonicity properties.

>>15858604
>1 is an abstract object comprised of two subjects
Mathematically speaking, 1 is comprised of zero subjects (because it is the multiplicative identity). Since the definition of primality, translated into your lingo, is that
>n is prime if and only if, whenever it can be comprised out of a finite collection of objects f1, f2, ..., fk (the "factors" of n), then there exists some factor fi that is identical to n
This means that the empty collection k=0 refutes that 1 is prime, by virtue of having no factor fi to identify with 1.

[Anonymous No.15858697]

>>15858693
...
Am I being trolled?

[Anonymous No.15858707]

>>15858697
I would certainly agree that it's not difficult to figure out that, for example, [math]\log_8(7)-\log_8(6) > \log_8(9 ) - \log_8(8) = \log_8(9) - 1[/math], but I see no reason to innately assume that your proposed inequality holds outside of "proof by lmao"

[Anonymous No.15858717]

>>15858695
>1 is comprised of nothing
Not exactly the strongest argument I was expecting desu

[Anonymous No.15858751]

>>15858707
Upon reflection, you're right. My notion and explanation would go beyond what was asked and wouldn't make sense probably. So yeah for all it matters it may as well be "proof by lmao". Sorry about that. I ended up being a bit of a jerk without intending to.

[Anonymous No.15858798]

>>15857957
Bump

[Anonymous No.15858806]

>>15858798
Read
https://phys.libretexts.org/Bookshelves/University_Physics/Book%3A_University_Physics_(OpenStax)/Book%3A_University_Physics_I_-_Mechanics_Sound_Oscillations_and_Waves_(OpenStax)/10%3A_Fixed-Axis_Rotation__Introduction/10.06%3A_Calculating_Moments_of_Inertia

[Anonymous No.15859219]

When does a system of linear equations has a finite number of solutions (assume it's consistent) even though there are more variables in the system than there are equations?

[Anonymous No.15859257]

>>15859219
Underdetermined systems, if consistent, always have infinitely many solutions.

[Anonymous No.15859327]

>>15859257
What about linear (in)dependence?

[Anonymous No.15859339]

>>15858751
its all good. Now go suck cock you little cock gobbler

[Barkun No.15859342]

>>15859339

[Anonymous No.15859343]

better to stab my arm pits or cut down my arm?

[Anonymous No.15859436]

>>15858589
Consider [math]f(x) =6^{12x} [/math] and [math]g(x) = 8^{12x}[/math] .
They are clearly strictly monotone functions and
[math]f(\log_6(7)) = 7^{12} = 13841287201 > 13060694016 = 6^{13} = f \left( \frac{13}{12} \right) [/math]
[math]g(\log_8(9)) = 9^{12} = 282429536481 < 549755813888 = 8^{13} = g \left( \frac{13}{12} \right) [/math]
So [math] \log_6(7) > \frac{13}{12} > \log_8(9)[/math]

[Anonymous No.15859456]

Serge Lang's Basic Mathematics:

In the chapter of polynomial functions, at pages 319-320, the author states and proves that we can describe a function of degree n as f{x) = (x - c)g(x), with g(x) of degree n-1, and where c is a root of f(x). All good.

Then he gives a little remark, and arrives at the conclusion that the greatest coefficients of f(x), g(x), which are An, Bn, respectively, are equal.

How does he arrive at the conclusion that An=Bn?


Remark. Let us look more carefully at the polynomial g which we obtained
in the proof. When we expand out a power
((x - c) + c)^k,
we get a term (x — c)^k, and all other terms in the sum involve a lower power
of (x — c). Hence the highest power of (x — c) which we get is the n-th
power, and this power comes from the expansion of
((x - c) + c)^n.
Thus the term with the highest power of (x — c) can be determined explicitly,
and it is precisely
An(x - c)^n
In other words, we have
Bn = An
Hence the polynomial g which we obtain has an expansion of the form
g(x) = Anx^(n-1) + lower terms.

[Anonymous No.15859467]

>>15859219
The set of solutions of a system with m equation in n variables with coefficients in a field F is either the empty set or an affine subspace of F^n.
The only way you can have more than one solution without having infinite solution is if the coefficients come from a finite field.

[Anonymous No.15859517]

>>15859456
He is saying that, in the expansion of ((x-c)+c)^n, you get some amount of multiples of the term (x-c), multiplied with some amount of multiples of the term c.
Since you have n terms in total, and n multiplications per term, if they are all (x-c) then there can be no terms of c, so that the coefficient of the term is 1 (multiplied by the coefficient of f, a_n).
Since you called this b_n in g, the two are equal.

[Anonymous No.15859549]

>>15859467
Tbh I don't know what that means. Okay, here's what's bothering me actually:
[eqn]
2r+p=11 \\
q+r+p=15 \\
q+2b=15 \\
2b+k=9
[/eqn]
There are lots of such similar examples in the workbook. All the variables should have definitive constant values in this system, but I don't know how to figure them out.

[Anonymous No.15859569]

>>15859549
>Tbh I don't know what that means.
To put it as simply as possible: The only time you're getting finitely many solutions, and not just zero, is if you're working in modular arithmetic (in which case, your infinitely many solutions are compressed to finitely many because there are only finitely many things to work with).
anyway your workbook is fucking with you. just a little bit of substitution and Gaussian elimination should be enough to convince you that you can write all four other constants in terms of the fifth, so unless one of them is given a definite value you cannot give one to any of the others

[Anonymous No.15859606]

How do I make this squiggly line ine in tikz?

[Anonymous No.15859619]

>>15859517

im clueless

for example, let n=2, ((x-c)+c)^2 expanded is (if I'm not mistaken in what an expansion is):

((x-c)+c)((x-c)+c) = (x-c)^2+2c(x-c)+c^2

I undestand that he describes this as b_n(x-c), where
b_n=((x-c)^2+2c(x-c)+c^2)/(x-c)^2

how does he get to b_n=a_n from there?

[Anonymous No.15859632]

>>15859619
*He shorthands (x-c)^2+2c(x-c)+c^2 as b_n(x-c)^2, and I assume
b_n=((x-c)^2+2c(x-c)+c^2)/(x-c)^2

In the previous page, (a_n)(x^n)=(a_n)((x-c)+c)^n, how does this relate to b_n(x-c)^n?

[Anonymous No.15859706]

>>15859456

https://www.youtube.com/watch?v=FlOknoaxg5g at 14:09
proof of this? i've spent +5 hours on this, it blows my mind lmao

[Anonymous No.15859718]

>>15859619
>>15859632
>>15859706
You are correct in your understanding of an expansion. Notice that you have three terms, each consisting of some 'amount of' (x-c) terms and some amount of c terms, so that the amounts per term add up to 2.
Also, the only term of the polynomial that can give a power of n is x^n=((x-c)+c)^n, and only in one way (n multiplications of (x-c)).
In the original polynomial f, this has coefficient a_n, and in g it has b_n.
These must then be the same (I think a slight generalization of this is also proven a few pages down, for all coefficients).
In general this would follow from the binomial theorem, which you don't know yet.

[Anonymous No.15859759]

>>15859718

Thanks for the help, I think I'm close to a breakthrough

[Anonymous No.15860068]

Is solving rigorous problems of physics,chemistry,maths, engineering necessary for being a good researcher/engineer? Something like David morin and rudin, are those necessary?

[Anonymous No.15860080]

>>15860068
No, it's necessary if you want to be based

[Anonymous No.15860327]

>>15860068
whats important is if you can hear the music not read it on sheet; can you hear the music?

[Anonymous No.15860522]

What's your go to source of new information?

>Google
Enjoy pages upon pages of shitty blogs and payed articles that hacked algorithm enough to show up in your results
>youtube
9/10 videos are made for people with attention of a gold fish. Out of the rest 9/10 don't bothers with quoting their sources. And out of those who do, 10/10 exaggerate and misrepresent them to have a better clickbait.
>books
99/100 won't bother with quoting their sources and are filthy bait, that got 5/5 reviews because of a good writing style.
>scientific journals and articles
Usually not free. Most often they are overly specific, so if you want to learn about any real life issues you have, you'll have to spend weeks going through them and writing your own summary

[Anonymous No.15860540]

>>15860522
>What's your go to source of new information?
1. A collection of every search engine, search operators
2. Collection of websites archiving forums and other content
3. Aggregators (reddit et al)
4. open science or open access journals and related including "pirated"
5. "closed" (non-searchable) platforms and communities (discord, twitter, anything generally not wanting to be on search results)
6. Collection of government websites with data portals and separately archived data because it likes to disappear behind a paywall

It helps a lot to keep these in lists categorized by type, and abstractly "how to find info" intersects with data hoarders, "open intelligence", etc. Search engines are especially worthless these days if you don't get real fucking creative with search operators and deliberately confuse the filtering engine with nonsense in between what you actually want to find.

I'd also recommend keeping accounts for things in another list and all separate from one another as much as possible. One "bare minimum" expense is having a throwaway phone for authorizations/apps if you don't want to sell your soul for data access.

[Anonymous No.15860575]

Welp I don't think I'm gonna get into graduate school, so I'm just gonna draw furry porn for a living to pay off my undergrad debt in mathematics.
I am NOT gonna fucking pay for a fucking masters either.
Is there anything I can do with a Math BS?
How about actuary?
How do I become one of those?
Need help, right now in my life my choices are be homeless or an hero.

[Anonymous No.15860582]

>>15860575
find a computational engineering subfield, or data science. Lots of options

[Anonymous No.15860584]

>>15860582
What do you mean? How do I find one of those?

[Anonymous No.15860627]

>>15860584
search *computational/software* *engineering discipline* jobs - tack on *modelling/simulation/analytics* if needed

light up some incense and meditate without eating for minimum 24 hours to find the one right for you

[Anonymous No.15861052]

>>15860627
Like this?

[Anonymous No.15861078]

>>15861052
yea it's over for you, try wendys

[Anonymous No.15861081]

How long did it take most of you to get through Alberts? What books did you study alongside it, and how did you manage your time? I'm trying to get through it alongside Lehninger and(if I get through a lot in one day) Volume 1 of Apostol's Calculus. I can't tell if I'm being overambitious or I've just been so lazy all this time that a reasonable load seems big to me.

[Anonymous No.15861087]

>>15861078
Wendy's needs applied mathematicians with expert knowledge in string vibrations?

[Anonymous No.15861166]

What's stopping us from being able to predict side effects and outcomes of psychiatric medication before a patient takes them?

[Anonymous No.15861177]

>>15861166
Brain's complicated

[Anonymous No.15861181]

>>15861177
Of course... but surely there's something to model? Or maybe, at the very least, statistics and DNA fingerprints?

[Anonymous No.15861190]

>>15861181
A lot of how we think the brain works is highly speculative and more based on correlation than anything else. We really don't understand it very well. Make of that what you will.

[Anonymous No.15861195]

>>15861087
try asking a gpt service like phind.com

[Anonymous No.15861302]

What's the difference between f=ma vs p=mv? Both calculate force right? I "get" momentum is supposed to be to calculate the force of mass that's in motion, so why is net force based acceleration?

[Anonymous No.15861307]

>>15861302
Momentum is not force, they measure different things. Force is the time derivative of momentum.

[Anonymous No.15861311]

>>15861307
Okay? But when something hits another object, it has a speed and won't accelerate any more, so at that point we only need to worry about the velocity right? So why should we care about the acceleration at that point? I'm not trying to be frustrating, it's just confusing to me

[Anonymous No.15861319]

>>15861311
The force is only applied at the moment of impact, when there IS an acceleration. It's an instantaneous thing, while momentum is not.

[Anonymous No.15861325]

>>15861319
Then what are we doing when we're calculating momentum?

[Anonymous No.15861340]

>>15861325
You're... calculating momentum?
As the other guy said, force is just a change in momentum over time, much as acceleration is just a change in velocity over time. They're two separate things.
A 1-kg object moving at a constant 1 m/s is not accelerating as is thus not subject to any net force, but it still has a momentum.

[Anonymous No.15861668]

Why do people always say distances in space are unimaginable when i can boot up space engine and get a good idea.

[Anonymous No.15861673]

>>15861668
>Why do people always say
stop hanging out around dumb people

[Anonymous No.15861860]

I'm a dumb retard and got a shitty bachelors degree that I never used.
If I do OSU's online CS degree will I have a chance to get a dev job?
The only other job I can think of starting at this point is accounting.
I'm also strongly considering suicide.

[Anonymous No.15861862]

>>15861860
> OSU's online CS degree
The program would take around 2 years to finish.
I'm willing to work hard to unfuck myself but I'm also scared that I end up doing it for nothing.
What do?

[Anonymous No.15861865]

Suppose I have a sequence of functions:
[math] f_{1} (x_{0} \rightarrow x_{1} ), f_{2} (x_{1} \rightarrow x_{2} ), \dots f_{n} (x_{n-1} \rightarrow x_{n} ) [/math].
What do I call the function that takes [math]x_0[/math] to the [math]n[/math]-tuple [math] x, x_{1}, x_{2}, \dots x_{n} [/math]?
Functions, transformations, mappings, morphisms, whatever you call them, what is the name of this superset of a sequence of them?

[Anonymous No.15861934]

>>15861860
>>15861862
It might be the best to hang yourself

[Anonymous No.15861941]

>>15861860
>>15861862
>>>/g/
As far as I know the junior dev job market tightened quite drastically in the last few years.
It's still probably a good idea to ask in the relevant /g/ thread, but they might tell you the same thing as >>15861934, good luck.

[Anonymous No.15862040]

How can we find the inertia of non uniform bodies ? Like a rod with sphere, a box with sphere at corners

Assymetrical 3d shapes ?
Parallel axis theorem isn't useful everywhere

[Anonymous No.15862055]

>>15862040
Calculate the integrals

[Anonymous No.15862070]

>>15861865
You can just call it a function.

[Anonymous No.15862082]

>>15862040
*Moment of inertia

[Anonymous No.15862084]

>>15862055
Can't it we done if we have symmetric bodies with with multiple systems without integration and using parallel axis/perpendicular axis theorems ?

[Anonymous No.15862363]

>>15853222
does anyone know where I can download Strangs Introduction to linear algebra (6th edition)? I can only find the 5th edition on libgen.rs.

[Anonymous No.15862604]

let's say I want to find the operation that yields, say,
[math]f(f(f(x))) =F(x)F(x)F(x)F(x)[/math]
[math]f(g(h(j(x)))) = F(x)G(x)H(x)J(x)[/math]
or maybe
[math]f(f(f(x))) =F(x)+F(x)+F(x)+F(x)[/math]
[math]f(g(h(j(x)))) = F(x)+G(x)+H(x)+J(x)[/math]

or whatever. This is just an example, but I come up with these kinds of relations all the time for shits and giggles. Is there some field of math that would provide me with some toolset to actually find solutions to these (functional analysis?) or am I on my own here?

[Anonymous No.15862678]

>>15862604
here's another question
in trying to work out the "composition-to-product" operator, I note that while scalar multiplication is commutative, composition, in general, is not. The proposed operation would convert an order-sensitive operation into a non-order-sensitive operation, "losing information" in the process

Is this a genuine contradiction in the sense of a proof and it's meaningless to carry on, or does it just mean I need to be more nuanced in the approach?

[Anonymous No.15862698]

>>15853222
i continue this convo in the board chat

discord,gg/4channel

[Anonymous No.15863383]

can someone explain why excess omega 6 (from linoleic acid) bioacumulates/causes these problems in pic rel, rather than just getting excreted once the body has enough omega 6?

[Anonymous No.15863655]

>>15862678
>>15862604
You have entered the field of crankery. What do you mean by "operation that yields"?
Do you want some function P so that P(f(f(f(x))))=(F(x))^4 for all x?
In general, trying to find a function f so that f(a+b)=g(a,b) for some prespecified function g is not going to work well because then also f(a+b)=g(a+1,b-1).

[Anonymous No.15864163]

>>15857801
did you even read your textbook

[Anonymous No.15864177]

Does the division of colors of the rainbow holds any specific significance to physics?

We all heard of "the seven colors of the rainbow", but were they named subjectively or is there a reason for this division? I believe that comes from Newto, rightn?

Couldn't I say there are 50 or whatever colors (blue, blue-indigoish, blue-indigo, blueish-indigo, indigo...)? Couldn't I say there are two colors of the rainbow, one warm and one cold, then umbrella all the yellow/reds and blue/violets together?

When I look at a rainbow I can kind of identify the seven colors, but maybe it's because I'm looking for them.

[Anonymous No.15864191]

>>15864177
There's no special significance

[Anonymous No.15864194]

>>15864177

Found the Alan Watts fan

[Anonymous No.15864220]

which one is correct? wolfram alpha says first, but my book says second. can both be equal at the same time somehow?

[Anonymous No.15864232]

>>15864220
So you took my advice posted here.
>which one is correct?
Second one.
>can both be equal at the same time somehow?
No, since 1/r^3 is non-zero when r is non-zero

[Anonymous No.15864235]

>>15864191
Thank you

>>15864194
Namaste

[Anonymous No.15864254]

>>15864232
why is first one wrong? wolfram alpha says it's right
thank you for your reply, by the way

[Anonymous No.15864269]

>>15864177
It's more a mix of biology and subjectively than physics. We have photoreceptors for red, green, and blue. Everything else is shades we arbitrarily name. For example the English language had no name for orange until fairly recently when the eponymous fruit was brought to Europe. It's why we still say red-heads when today we would describe their hair as actually being orange.

[Anonymous No.15864279]

>>15864254
You can just compute [math] \Delta (1/r) [/math] directly for non-zero r to see that it gives you zero, so it can't be the first one. As to why the second one is right, see https://www.physics.uoguelph.ca/chapter-6-delta-function

[Anonymous No.15864290]

>>15864279
ok, the first one is calculated in polar coordinates, my bad.
but if you compute the laplacian of 1/r it gives you exactly 0 for all values of r, r=0 included. how come it's a dirac delta?

[Anonymous No.15864298]

>>15864290
1/r is not defined for r = 0, so the calculation which worked for non-zero r won't work at r = 0. To find [math] \Delta (1/r) [/math], you treat 1/r as a distribution instead of a function and then take the distributional derivatives of 1/r.

[Anonymous No.15864305]

>>15864269
Interesting. I was confused because even in that chart you have blue area bigger than cyan or yellow and I thought there could be a reason to stick to these color names, but I guess there is no importance. I didn't know about red heads/orange name. Cool, thanks.

[Anonymous No.15864325]

>>15864305
> you have blue area bigger than cyan or yellow
Again that's biology. If you look at that chart you will notice green is especially narrow because the human visual system has evolved to be especially sensitive to green, for obvious reasons, and we can distinguish different green-ish colors more readily than we can blues.

[Anonymous No.15864345]

A thorough reference for pretty much everything you'd ever want to know about the science of color vision:
http://www.handprint.com/LS/CVS/color.html

[Anonymous No.15864352]

Damn... First time in this thread and I feel like a caveman trying to understand why fire burns

[Anonymous No.15864365]

My book states
>Si(001) has two-fold symmetry
Why? It's a square, I'd expect a four-fold symmetry.

[Anonymous No.15864387]

>>15855456
Yes. I don't know either....

Yes

[Anonymous No.15864391]

>>15855747
Some igneous rocks like, olivine basalts, can be green

[Anonymous No.15864408]

>>15855456
I think the Steiner's theorem could help you out here.

[Anonymous No.15864415]

>>15864408
Steiner's theorem is the parallel axis theorem (which the anon mentioned)

[Anonymous No.15864433]

>>15864305
The partitioning of the spectrum into specific colours is entirely arbitrary. E.g. Japanese consider green to be a shade of blue. In English, the presence of "indigo" is just down to Newton having a fondness for the number seven.
Beyond that, colour theory is biology, not physics.

[Anonymous No.15864509]

>>15864345
Fantastic resource. Thank you.

[Anonymous No.15864598]

Let [math]X, Y[/math] be topological spaces. Am I correct in saying that sets of the form [math]U \times V[/math] with [math]U \subseteq X, V \subseteq Y[/math] open respectively form a basis of the product topology on [math]X \times Y[/math]?

[Anonymous No.15864601]

>>15864598
What you've described is the box topology, but they are the same when you are taking the product of finitely many topological spaces.

[Anonymous No.15864624]

Consider the vector space [math]\mathbb{Z}/p\mathbb{Z} \times \mathbb{Z}/p\mathbb{Z}[/math], where [math]p > 2[/math] is prime. How many subvector spaces does this vector space have? I think it's always 6. Is it correct?

[Anonymous No.15864647]

>>15864624
>There is one subspace of dimension 0.
>There are p-1 subspaces of dimension 1.
>There is one subspece of dimension 2.

1 + (p-1) + 1 = p + 1

[Anonymous No.15864652]

>>15864647
>There are p-1 subspaces of dimension 1.
Sorry it's actually p+1. I miscounted.

[Anonymous No.15864664]

>>15864598
In case it wasn't clear, >>15864601 is a yes.
>>15864652
[math]p^2 - 1[/math] non-zero vectors, [math]p+1[/math] spaces once we account for the multiplicative action from [math]Z_p[/math]. Looks good to me.

[Anonymous No.15864695]

>>15864647
This is already incorrect for p = 3, where there are 6. I don't follow your reasoning at all.

[Anonymous No.15864712]

>>15864664
For p = 2 you already have 5 subvector spaces, not 2 + 1 = 3 or 2^2 - 1 = 3. I don't get what you guys are on about. Did you check how many additive subgroups you can possibly have?

[Anonymous No.15864724]

>>15864695
See anon's correction in >>15864652 , there's a 0 dimensional space, p + 1 one-dimensional spaces and 1 bidimensional space. That's 1 + (p + 1) + 1 = 6 for p = 3.
>>15864712
p + 1 is the number of one-dimensional subspaces.
For p = 2, those are {0, (1, 0)}, {0, (0, 1)} and {0, (1, 1)}. Then the zero-dimensional and two-dimensional subspaces for 5, as you've pointed out.

[Anonymous No.15864749]

>>15864724
It makes more sense now. But I'm not convinced. What do the 6 one-dimensional subspaces of (Z/5Z x z/5Z) look like?

[Anonymous No.15864750]

I don't get this, shouldn't it be [math]\mathcal{F} = \textrm{set of functions from }\mathcal{B}\textrm{ to members of }\mathcal{S}[/math]?

[Anonymous No.15864774]

>>15864749
For any [math](a, b) \neq 0 \in \mathbb{Z}_p^2[/math], either [math]a = 0[/math], and then we can write [math](a, b) = b(0, 1)[/math] or [math]a \neq 0[/math] and we can write it as [math](a, b) = a (1, b/a)[/math].
This tells us that every vector is a multiple of one of [math]\{ (0, 1), (1, 0), (1, 1), \ldots, (1, p-1)[/math], so all the one-dimensional vector spaces are spans of one of those.

[Anonymous No.15864802]

>>15864774
And because of [eqn]\det \begin{pmatrix} 0 & 1 \\ 1 & b \end{pmatrix} = p - 1,\ \ \ \det \begin{pmatrix} 1 & 1 \\ a & b \end{pmatrix} = b - a \neq 0[/eqn]for all [math]0 < |b-a| < p[/math], the spanned subvector spaces are pairwise distinct?

[Anonymous No.15864841]

>>15864802
I wouldn't use determinants but sure, that works.

[Anonymous No.15864842]

>>15864841
Okay I got it, thanks

[Anonymous No.15865012]

https://www.amazon.com/AXTRA-12-Outlets-Commercial-Industrial-Environments/dp/B07KSLQ9GS
Is 400 joules enough protection if I'm gonna have two gayman PCs, a monitor, a desklamp, a printer, and a shredder plugged into it?

[Anonymous No.15865284]

As far as I understand, Bioengineering is just Biology + Chemical Engineering, and those respective lists on the wiki should prepare me for understanding the theory behind the field? Otherwise, is there anyone who has the authority to make a list for it on the wiki?

[Anonymous No.15865597]

>>15853222
should i drop out of an math major and pursue career in cybersecurity i cant take it anymore i wanna be simple again all this abstract thinking driving me nuts i feel like i would be a great at cybersecurity

[Anonymous No.15865616]

>>15865597
It pays very well and has good long-term career prospects just don't expect it to be "easy". There's a lot to learn if you want to be at the top of the field.

[Anonymous No.15865684]

>>15853222
what household chemicals do I mix to create hydrogen sulfide?

[Anonymous No.15865843]

>>15865684
lmao just get some hydrogen and sulfer and put it in a pressure cooker

[Anonymous No.15865949]

>>15865843
can't buy those at walmart.
I think a HCl based toilet cleaner combined with something with sulfur should work, need to find a sulfur something now

[Anonymous No.15866012]

How do i convince a cardiologist to look at my heart beyond an echocardiogram?
I'm 100% sure something is wrong.

[Anonymous No.15866102]

>>15866012
get a second opinion

[Anonymous No.15869501]

It's like my engineering textbook converts units with an exponent by exponentiating the magnitude as well. E.g. they convert [math]cm^2=10^{-4}m^2[/math]. Is this correct? What is the logic behind this?

[Anonymous No.15869518]

>>15869501
It might look a bit odd, but why wouldn't it be correct?

[Anonymous No.15869541]

>>15869501
This is just a convention that only applies the areas and volumes but not other physical quantities. The goal is that you have
(1 cm) * (1 cm) = 1 cm^2
rather than the more logical
(1 cm) * (1 cm) = 10^(-2) cm^2

[Anonymous No.15870197]

How does Dover get to sell the Jacobson books when Jacobson didn't die until 1999?

[Anonymous No.15870404]

does anyone have the link or archive of the old /sci/ wiki?
I'm not talking about this one https://4chan-science.fandom.com/wiki//sci/_Wiki

[Anonymous No.15870666]

If I throw a ball from one end of a plane to another while the plane is flying. It's speed will be faster if my frame of reference is the ground instead of inside the plane because the speed of the plane is being added. But if I move my frame of reference even farther lets say another planet, another galaxy etc... It should keep adding velocities right? So why can't the speed of the ball reach the speed of light from some really distant frame of reference?

[Anonymous No.15870683]

>>15869541
Not her, but why would the latter option be more logical?

[Anonymous No.15870753]

>>15870666
Because speed doesn't add linearly, if you boost into another frame of reference lengths contract and the passage of time slows down to keep the ball's speed under the speed of light. This sort of classical thought experiment is part of what led to the discover of special relativity.

[Anonymous No.15870809]

>>15853222
guys is Natrium and Chloride separated during water electrolysis ?
Basically if i have Distiled pure H2O and add NaCl will NaCl get electrolized aswell ?
i asked in chug but i figured i may try here aswell

[Anonymous No.15870818]

>>15856780
There are already programs that solve equations

[Anonymous No.15870902]

Why don't spiders emit a sweet scent like rotting fruit?

[Anonymous No.15870962]

>>15870809
sort of?
a significant difference in redox potentials means that it'll preferentially produce hydrogen over unionised sodium
and any neutral sodium it does produce will immediately react with the water to produce more hydrogen, returning sodium to the solution
but it'll also produce gaseous chlorine, especially as your solution gets more and more concentrated
so the sodium will never electrolyse in water, but the chloride will

[Anonymous No.15871013]

>>15870962
from what i already learned in internet if i have a NaCl water solution then H2 and Cl2 will gather at anode and Na at cathode but it will create NaOH
and NaOH is a better electrolyte than NAcL
so after a while i won't need to add salt to this solution ? i can just keep adding more water ?
oh also i need h2 for experiment with diesel engine generator so this is why i am asking this
also thanks

[Anonymous No.15871017]

>>15864177
>or is there a reason for this division
it's how God created this world :)

[Anonymous No.15871133]

how to solve using laplace transforms

[Anonymous No.15871291]

Do you have to follow the Chemistry wiki list strictly from top to bottom? I'm aware I need to finish Organic Chemistry, but could I skip Physical Chemistry for now and do Inorganic first?

[Anonymous No.15871888]

When we see the gaseous vapours form around dry ice, that's actually water condensing from the surrounding air correct? we are not actually seeing CO2 in gas form?

[Anonymous No.15871933]

>>15853222
give me undergrad answer as to the insolvability of the quintic

[Anonymous No.15871942]

>>15871933
youtube

[Anonymous No.15872465]

/lit/ here, hope this is the right thread.
I would love some advice for a sci-fi short story I'm developing, as I haven't dealt with any maths/physics since I graduated high-school over a decade ago.
The story has a plot device that involves matter expanding concentrically/spherically at a rapid pace. I want to express that the rate of expansion declines as a function of area (already) covered, where the initial speed/rate is significant (~1% c) but the decline also 'speeds up' so that by the time the total area covered reaches 50km the speed drops down very fast to speed of sound levels and then remains constant (or rather any further decline becomes so miniscule that it seems practically constant by human standards).
In the story this is supposed to function like a law of nature, so I want to express it as a formula. Any help would be much appreciated. As I said I'm not familiar with math/physics, so please excuse the poor explanation...

[Anonymous No.15872509]

>>15872465
look into logarithmic growth

[Anonymous No.15872519]

>>15872509
I would have preferred a spoonfeed, but thanks, it's a start.

[Anonymous No.15872536]

>>15872465
Your readers wouldn't care.

[Anonymous No.15872541]

>>15871133
1. Apply Laplace transform
2. Solve for the Laplace transform of y
3. Apply Inverse Laplace transform

[Anonymous No.15872554]

Now that mankind knows there are a gigantic amount of galaxies, stars, planets, moons, rocks out there, under a gigantic set of different scenarios, it is a consensus that there is not one, or ten planets that host life and/or civilizations, but a gigantic amount of them, in several stages of development at any given time ever since the elements got stable enough for them to come about. At this moment, we are having catastrophes and utopias going on out there. Do you think that we are ethically responsible for speeding up our means to reach and act upon those things, mediate alien wars, help with disaster response like evacuating a star system, save endangered alien species, create terraforming investment and real state at a reasonable price throughout the galaxies, bring technology to aid those in need? How difficult will that be, to choose sides in intergalactic struggle with hundreds of millions of years of recorded history? Wouldn't it be the case that we become colonies of other civilizations and oppress others, perhaps at the same time? Can we save the universe? From what? For what? Can we keep everything and everyone alive and well for the infinite of time? Do we want that? Shouldn't we be devising a philosophy that can make us surf and flow, not only humans and Earth's flora and fauna, but something for the entire universe to withstand the trip towards the ultimate ash of heat death and the next conformal cycle? If an ant decides and acts to stop a human war, would you call it delusional or brave?

[Anonymous No.15872646]

>>15872519
the derivative of a logarithm (i.e. its rate of growth) starts fast, but then approaches zero, which is consistent with your description. theoretically, the object will continue growing, but on a human timescale it'll slow to effectively zero.

[Anonymous No.15872709]

Ok, so I'm looking for a specific paper that came out back in 2018 or so. It was about the discovery of virus-like particles naturally produced in the brain. I can't seem to find it.

pic unrel, archeal viruses are cool looking

[Anonymous No.15872765]

>>15853222
Can someone explain the Grand Hilbert Paradox?
A hotel that has an infinite number of full rooms and no empty rooms can fit an infinite number of new guests by creating new rooms that are already full and moving existing guests there. which sounds stupid and so i'm poisting here
I guess there must be more to it, because that's stupid. If it had an infinite umber of empty rooms and an infinite number of full rooms, it wouldn't be a paradox.

[Anonymous No.15872774]

>>15872765
>All natural numbers 1,2,3,4,5,6...
>infinite
>All even natural numbers: 2,4,6,8,10,12...
>also infinite
>but with half the numbers

[Anonymous No.15872846]

>>15872774
1-12 and all numbers beyond are included in the set of infinite full rooms in the hotel. Where are the new guests going?

[Anonymous No.15872851]

I'm trying to show that the remainder of the stone-cech compactification of the reals [math]\beta\mathbb{R}\setminus\mathbb{R}[/math] is uncountable but I don't have a grip on elements of [math]\beta\mathbb{R}\setminus\mathbb{R}[/math] at all. Is there some characterization?

[Anonymous No.15872892]

>>15872846
You ask the guests in room 1 to move to room 2, the guests in room 2 to move to room 4, the guests in room 3 to move to room 6, etc.

[Anonymous No.15873047]

I graduated in May with a BS in mechanical engineering. Yesterday I applied for an online master's program in facilities management. Should I expect the masters to be harder or easier than my undergrad. I work full time, so I'm trying to figure out if I should take 6 or 12 credit hours per semester

[Anonymous No.15873117]

Why does people not realize, we can obtain energy by cooling something?

Newtons law of thermodynamics doesn't say, e.g. if we cool sea water, that it is a closed system, therefore we can have loads of energy by constructing such device.

[Anonymous No.15873148]

>>15873117
Second law of thermodynamics

[Anonymous No.15873344]

>>15873148
Yes, we cool something therefore we obtain energy.

That's what those laws are about.

[Anonymous No.15873515]

>>15871888
any buddy?

[Anonymous No.15873685]

Is there a cheap and painless way to an hero myself?
My life has been getting worse and worse for the past decade and it's mostly been my own fault.
I have also realized I lack the ability to fix it.
I don't really want to continue.

[Anonymous No.15873770]

Why did it take life so long to go from photosynthesis to eukaryotes?

[Anonymous No.15873799]

>>15873770
It's not that long honestly.
Though to answer your question, I'd wager it was a result of most life ostensibly being confined to hydrothermal vents and other somesuch nutrient sources, thus most life staying around these sources until it developed the metabolism necessary for surviving outside of hydrothermal vents. Then, they'd need to reach the surface and develop photosynthesis. There also might not have been enough nutrients dissolved in the primordial water column (particularly bioavailable carbon) for most life to radiate outside of the deep sea.

[Anonymous No.15873841]

>>15873799
>It's not that long honestly.
1.5 billion years or so is one third of Earth's history. Granted, I know it's not entirely accurate and the lines are quite blurry, but still - the fact it took that much time to go from photosynthetic organisms to eukaryotes is just mind-blowing.
>There also might not have been enough nutrients dissolved in the primordial water column (particularly bioavailable carbon) for most life to radiate outside of the deep sea.
Interesting. Is it possible that geological processes helped change that to some degree?

[Anonymous No.15873877]

>>15873841
>Is it possible that geological processes helped change that to some degree?
Absolutely. There is also the fact life changed the climate and the composition of the atmosphere. Complex life requires oxygen and not a small amount of it. That required enough photosynthesis and for long enough to produce it.

[Anonymous No.15874046]

>>15873685
It's never too late to turn your life around. My brother an heroed in 2020. He was a 24 year old software engineer. It's was the most horrible loss our family has ever felt. If he'd spent the last three years learning to be happy instead of in the ground, i believe he'd be ok. Don't let this year be your last. If only you could see how sweet life can be for you

[Anonymous No.15874060]

>>15853222
How do I calculate the following integral? I don't know where to start on this one.

[math] \int \frac{\ln (a +b\cos(ct))}{d+t^2} [/math]

[Anonymous No.15874065]

>>15874060
Forgot to show what the integral was with respect to- it's with respect to t.

[math] \int \frac{\ln (a +b\cos(ct))}{d+t^2} dt [/math]

[Anonymous No.15874165]

>>15874065
What context is this coming up in?
a quick check with WA is saying that there's no closed-form representation of the antiderivative

[Anonymous No.15874484]

Any chemist want to explain the actual physics behind 2D NMR? I understand how to read the plots and my understanding of 1D NMR is the following:
>nuclei have spin that are random and same energy
>with a magnetic field applied, the spins will align with or against the field and create different spin states of energy
>radio frequency excites low energy spin state (z axis) to high energy state (xy axis)
>process of relaxation from excitation gives an FID signal that gives the peaks when Fourier transform is applied
I can’t find any good visualization for how 2D NMR works and the best i find on youtube are pajeets reading from slides

[Anonymous No.15874581]

So I pasted what I think is the DOI into sci-hub.st and it didn't have it. What do I do now?

[Anonymous No.15874592]

>>15874581
>Tips for asking questions here:
>>attach an anime image
Please accept my offering of mommy Misato

[Anonymous No.15874599]

>>15853641
the two left ones come from assuming 'a' is a constant.
then just integrate over time, twice.

[Anonymous No.15875037]

Is the highlighted part wrong?

[Anonymous No.15875047]

>>15875037
Yes.

[Anonymous No.15875230]

>>15874484
Pls chemfags I can’t listen to another pajeet

[Anonymous No.15875514]

>>15874581
post screenshot of doi in search field

[Anonymous No.15875631]

>>15874581
If you are a uni student or know someone who is, ask them to check the online library since the have a bunch there

If you can’t find it there either just cite it without reading, no one’s going to go through that much effort to find a paper from 1943 that’s probably already been discussed in a review

[Anonymous No.15875638]

>>15874581
if it's modern then just straight up ask the researchers for a copy

[Anonymous No.15875642]

Ok I might just be retarded, but is there a difference between[math] |x+y|^2 [/math] and [math](x+y)^2[/math]? Or replace x+y for any function, specifically I'm looking at Parseval's Identity right now, and he decided to use the absolute value instead of just parentheses I assume there's a reason for that.

[Anonymous No.15875681]

>>15875642
Of course it's different in complex spaces where the absolute value may eliminate the imaginary part of a number.

[Anonymous No.15875683]

>>15875642
|x+y|^2 always gives a positive answer, even if x+y is imaginary

[Anonymous No.15875764]

>>15871133
1. Laplace transform of both sides:
s^2 Y(s) + 9 Y(s) - s y(0) - y'(0) = 108/s^3 - 9/s^2 + 39/s
=> (s^2+9)Y(s) = (108-9s+39s^2)/s^3 + s y(0) + y'(0)
2. Solve for Y(s):
Y(s) = (108-9s+39s^2)/s^3(s^2+9) + (s y(0) + y'(0))/(s^2+9)
3. Partial fraction decomposition with denominators s, s^2, s^3, s+3i, s-3i:
Y(s) = 3/s - 1/s^2 + 12/s^3 + (3y(0)-9 + (y'(0)+1)i)/6(s+3i) + (3y(0)-9 - (y'(0)+1)i)/6(s-3i)
4. Inverse Laplace transform:
y(t) = 6t^2-t+3 + e^-3it (3y(0)-9 + (y'(0)+1)i)/6 + e^3it (3y(0)-9 - (y'(0)+1)i)/6
5. Convert complex exponentials to trig:
y(t) = 6t^2-t+3 + (y(0)-3) cos(3t) + ((1+y'(0))/3) sin(3t)

Alternatively, you can leave s^2+9 unfactored which eliminates the need for step 5 but you have to remember the transforms for sin/cos (otherwise, L{u(t) t^n e^-at}=n!/(s+a)^(n+1) is sufficient for every linear ODE where the coefficients are polynomials in t).

[Anonymous No.15875818]

How much Organic Chemistry would I have to brush up on before I stop needing to Google my way through every paper?(If the answer is never, that's fine too.) I'm working through Clayden and looking at abstracts to keep myself interested.

[Anonymous No.15875826]

Has anyone else had trouble finding ACS Journal of Organic Chemistry articles on Sci-Hub? Even as far back as August 4th I'm coming up dry.

[Anonymous No.15876049]

Are there any animals with actual sharp teeth? Knife-like teeth, not kinda-pointy bullshit.

[Anonymous No.15876053]

>>15876049
*any mammals
I know about shark teeth.

[Anonymous No.15876054]

>>15876049
Sharks

[Anonymous No.15876073]

>>15876049
Tiger?

[Anonymous No.15876111]

would like someone to solve parts a and b just to get me started

[Anonymous No.15876135]

How do you construct a matrix whose null space has a given basis?

[Anonymous No.15876217]

>>15876135
Remember that the kernel of A is equat to the column space of A^T.

[Anonymous No.15876225]

>>15876135
Remember that the kernel of A is equal to the orthogonal complement of the column space of A^T.

[Anonymous No.15876347]

on the off-chance someone knows
I'm working a problem involving path losses for geostationary satellite transmission. It's just frequency-dependent inverse square stuff, simple enough
[math]L_p = (\frac{1}{4000pi\frac{R}{\lambda}})^2[/math]
where R is taken to b 38,500, and the uplink (earth-to-satellite) frequency is 14.15 GHz
this yields -207.17 dB for the loss, which is correct

Now for the downlink (satellite-to-earth), the frequency is 11.45 GHz. Evidently there is a multiplicative term now,
[math]L_p = (\frac{1}{4000pi\frac{R}{\lambda}})^2\cdot (\frac{f_{up}}{f_{down})^2[/math]
which changes the path loss from -207.17 to -205.33 dB. This multiplicative frequency-scaling term is never mentioned in either the textbook or lecture notes, and I'm at a complete loss as to why it's there given that (save for the frequency), the path loss feels like it should be symmetric for identical distances

does anyone have any idea what this term is

[Anonymous No.15876350]

on the off-chance someone knows
I'm working a problem involving path losses for geostationary satellite transmission. It's just frequency-dependent inverse square stuff, simple enough
[math]L_p = (\frac{1}{4000pi\frac{R}{\lambda}})^2[/math]
where R is taken to b 38,500, and the uplink (earth-to-satellite) frequency is 14.15 GHz
this yields -207.17 dB for the loss, which is correct

Now for the downlink (satellite-to-earth), the frequency is 11.45 GHz. Evidently there is a multiplicative term now,
[math]L_p = (\frac{1}{4000pi\frac{R}{\lambda}})^2 \cdot (\frac{f_{up}}{f_{down}})^2[/math]
which changes the path loss from -207.17 to -205.33 dB. This multiplicative frequency-scaling term is never mentioned in either the textbook or lecture notes, and I'm at a complete loss as to why it's there given that (save for the frequency), the path loss feels like it should be symmetric for identical distances

does anyone have any idea what this term is

[Anonymous No.15876390]

>>15876350
ok I'm just a braindead mouthbreather, I had plugged in the uplink value for the frequency, instead of the downlink frequency

[Anonymous No.15876842]

n(A) = K, then find the number of Relation R from A to A such that

R is reflexive
Can someone pls explain how is the answer 2^(K^2 - K)

??

[Anonymous No.15876860]

How to convert ideal voltage to ideal current sources and vice versa?

[Anonymous No.15876878]

>>15876842
Use a bijective proof
https://en.wikipedia.org/wiki/Bijective_proof?useskin=vector
It's clear that there is a bijection between the reflexive relations on A and the set of KxK matrices with entries in {0,1} that are 0 on the diagonal. (Label the elements in A from 1 to K and make the matrix entry at (i,j) = 1 if (i,j) in R and 0 otherwise).
Such a matrix has K^2 - K entries outside of the diagonal and each of those entries can take two values so there are 2^(K^2 - K) of them.

[Anonymous No.15877187]

>>15876878
Thanks, anon

[Anonymous No.15877204]

>>15876860
https://en.wikipedia.org/wiki/Th%C3%A9venin%27s_theorem
You need at least one resistance; you can then swap between a voltage source (with a parallel resistance) and current source (with a series resistance) using Ohm's law: V=IR <=> I=V/R.

[Anonymous No.15877255]

>>15864365
Anyone pls? I still haven't figured this out

[Anonymous No.15877278]

I've got some new neighbours moved in to an industrial unit next door. They refurbish car wheels and were venting dichloromethane fumes, which was getting into my unit until health and safety told them to stop.

Now there's a really strong almond smell coming in, any idea what they might be fucking around with now?

[Anonymous No.15877289]

Imagine you have a phone with an accelerometer lying flat and firmly attached to the dashboard. When you accelerate and then drive with a constant speed and then slam on the breaks, what should it read in all 3 cases? I think it should be 1. positive 2. 0 3. negative. Now imagine your phone is easily sliding on a slick surface with zero friction along the front/rear axis. What should it read in all three cases? It would move back on acceleration and then move forward on deceleration, correct? I can't figure out how inertia would change the accelerometer's readings. Would it read zero in all three cases? Since as the car is accelerating forward, the phone is sliding backward with the same rate?

[Anonymous No.15877334]

>>15877278
Well, cyanide smells of almonds

[Anonymous No.15877354]

>>15864365
Two of the corners are connected to the interior structure, two aren't. So a 90° rotation doesn't map the structure onto itself.

[Anonymous No.15877428]

>>15876049
Warthog tusks have very sharp cutting edges on the end. The lower tusk is honed against the upper through natural use

[Anonymous No.15877432]

>>15853222
I haven't taken physics aside from ap in highschool 10 years ago.
That being said, isn't special relativity unfalsifiable? How exactly could one show that light in a vacuum isn't the fastest? Putting that aside, couldn't you still have a nonblock universe if you assume that stuff you cannot observe exists? If it's outside your light cone it cannot possibly happen simultaneously to anything you observe. Does that imply that a barber trimming the back of my head can't happen at the same time I'm looking at him shave my head in a mirror. That definition of "now" seems a bit limited.

[Anonymous No.15877457]

>>15877354
Thanks. I thought (001) meant strictly what goes on in the green plane, but for any surface phenomena it makes sense that the nearby underlying structure plays a role.

[Anonymous No.15877486]

>>15875037
[math]\ln(0)[/math] is undefined, not [math]0[/math].

[math]e^x[/math] is never [math]0[/math], so the equation [math]2e^x=0[/math] has no solutions

[Anonymous No.15877513]

>>15877432
you can measure things other than light. if you had a hypothetical particle that travels faster than light, just put up a detector far away from it and see if it hits the detector before light from the same area does.
anything you observe has already occurred, depending on how far away from the event you are then the time it takes the light to reach you could be non-negligible (e.g. planning space communications). Things can only be "observed to happen at the exact moment they happen" if you're at the same point in space

[Anonymous No.15877519]

>>15875818
unless it's your hyper specific field of study, the answer is never. but you'll get to a point where you only google a few things that are relatively unheard-of outside of the subtopic

[Anonymous No.15877564]

>>15856648
It's nocebo effect. Cops have managed to convince each other its super dangerous so they have a panic attack and faint when they touch it. It'd be the same if you threw sugar at them and they thought it was fentanyl.

[Anonymous No.15877591]

Can someone tell me why Weinberg (Quantum Theory of Fields 1, chapter 6.4, page 287) states that in this case, the lines on vertices produced by functional derivatives of the S-Matrix would only be internal? As far as I understand it, for a single derivative in ε(x), it produces a further operator O(x) in the time ordering, consisting of a product of fields. These fields can be contracted with the creation/annihilation operators in the initial and final states, connecting the external momenta with the O(x) vertex according to the Feynman rules described earlier in this chapter. The only difference to the normal V potentials in the time ordering is that for O(x), one does not integrate over the spacetime x. I think it must be related to that, but I can't see why and how.

[Anonymous No.15877645]

Ok I've looked all over the place, can someone please tell me how the real case for Parseval's identity ( [math]\dfrac{1}{\pi}\int\limits_{-\pi}^\pi |f(x)|^2 dx = \dfrac{a_{0}^2}{2}+\sum\limits_{n=1}^\infty (a_n^2+b_n^2)[/math]) is demonstrated? According to Wikipedia you're supposed to use [math]\{\dfrac{1}{\sqrt{2}}, cos(nx), sin(nx)\}, n \in |N, \langle f|g\rangle = \dfrac{1}{\pi}\int\limits_{-\pi}^\pi f(x)g(x) dx [/math], but I can't figure that shit out.

[Anonymous No.15877659]

1)lets say f: X -> R, where f(X)={1,2,3,4}
g:{1,2,3} -> R, is it possible to construct a composition of f and g then? I know when f(X) is a subset of the domain of g then it can't and when f(X) ={1,2,3} then it also can. It also seems that this should be possible since g maps all of the elements of it's domain, but I don't know clearly.
2)also when we construct a composition of f:X->Y and g:Y->Z, we're basically assuming that f(X)=Y right?

[Anonymous No.15877677]

>>15877659
1) No, because 4 is not in the domain of g, so [math]g\circ f[/math] is not defined.
2) No, only that [math]f(X)\subset Y[/math] which it is by your assumption f:X->Y.

In general, we only compose functions when the codomain of the first matches the domain of the second, even if the first function is not surjective.

[Anonymous No.15877681]

>>15877677
>In general, we only compose functions when the codomain of the first matches the domain of the second
Might be better to say range than codomain, since codomains can get a little arbitrary

[Anonymous No.15877703]

>>15877677
but if f(X)!=Y then every element of g won't be mapped, for example let f:X->R, g:R->R then and f(X)=R\{0},which is a subset of R, then you can't construct the composition of f and g. so f(X) or the range of f must equal the domain of g.

[Anonymous No.15877707]

>>15877513
>before light from the same area does
What do you mean by this? Define before.

[Anonymous No.15877711]

>>15877703
>but if f(X)!=Y then every element of g won't be mapped,
There is no need for every element of g's domain to be mapped.
If we let, say, f(x)=0 for all real x, and g(y)=y for all real y, then g(f(x))=g(0)=0 and there's no problem

[Anonymous No.15877717]

>>15877711
>There is no need for every element of g's domain to be mapped.
Isn't that literally the definition of a function?

[Anonymous No.15877719]

Why did democrats actually oppose nuclear power, supporters and politicians.
Maybe not /sci/ related enough, but where am I gonna ask this /pol/? /his/? LMAO.

[Anonymous No.15877720]

>>15877717
yeah, I misspoke. I'm tired.
Rather, there is no need for f to map to every element of g's domain.

[Anonymous No.15877728]

>>15877645
Just insert the fourier series for f(x) and it collapses pretty nicely.

[Anonymous No.15877793]

>>15853222

Find the typo error if you can please, i am tires of this shit
True version is the one below
A) (1 - ((45!/(5!*40!)) / (50!/(5!*45!))) - ((45! / (4!*41!))*(5!/(1*4!))/(50!/(5!*45!))* (1/(11!/(2!*9!))) + ((1 - (45!/(5!*40!)) / (50!/(5!*45!))) * (1/(11!/(2!*9!)))
B) (1 - ((45!/(5!*40!)) / (50!/(5!*45!)) - ((45! / (4!*41!))*(5!/(1*4!)))/(50!/(5!*45!))) + (1 - (45!/(5!*40!)) / (50!/(5!*45!)))*(1/(11!/(2!*9!)))
A) (1- (45 choose 5) / (50 choose 5) - ((45 choose 4) * (5 choose 1)) / (50 choose 5)) * (1 - 1 / (11 choose 2)) + (1- (45 choose 5) / (50 choose 5)) * (1 / (11 choose 2))


B) (1- (45 choose 5) / (50 choose 5) - ((45 choose 4) * (5 choose 1)) / (50 choose 5)) + ((((45 choose 4)*(5 choose 1))/(50 choose 5))) * (1/(11 choose 2)

[Anonymous No.15877819]

>>15877707
? if the particle and the light are emitted at the exact same spacetime coordinate, but the particle reaches a point earlier than the light reaches that same point
are you being purposefully obtuse?

[Anonymous No.15877823]

>>15877719
because politicians are not acting for the people, they're acting for money and power. pushing other renewables is safer to the people because there's less pushback.
>muh weapons
>muh disasters
>muh startup cost
these scare the average person, who just so happens to make up the majority of the voter base (for both parties)

[Anonymous No.15877966]

[math]\sum{a}^{b}[/math]
Test

[Anonymous No.15877968]

>>15877966
Test 2
[Math] \sum{a}_{b}2x+3[/Math]

[Anonymous No.15877972]

test 3
[math]\int_a^b f(x) dx [/math]

[Anonymous No.15877996]

Im retarded please help. I have the following equation
[math]L(t) = 25t + 300[/math] where t is the year, and it tells me how much a population decreased that year. I want to know how much the population decreased after 2 years. So i take integral
[math] g(t) = \int_ 25t + 300 dt = \frac{25{t}^{2}}{2} + 300t [/math]

So then g(2) = 650

But then if I take L(0) + L(1), I get 300 + 325 = 625

Why is there a 25 difference? Shouldn't they be the same value?

[Anonymous No.15877998]

Im retarded please help. I have the following equation
[math]L(t) = 25t + 300[/math] where t is the year, and it tells me how much a population decreased that year. I want to know how much the population decreased after 2 years. So i take integral
[math] g(t) = \int 25t + 300 dt = \frac{25{t}^{2}}{2} + 300t + C[/math]

So then g(2) = 650

But then if I take L(0) + L(1), I get 300 + 325 = 625

Why is there a 25 difference? Shouldn't they be the same value?

[Anonymous No.15878142]

>>15877998
With the integral method, you get the area under the curve L(t) from 0 to 2. With the L(0)+L(1) method, you get a lower approximation of that area, because you're basically assuming that the function is constant from 0 to 1 and has the value L(0). But it is rising, so this approximation misses that extra area. The integral is basically defined as adding an infinite number of rectangles, in your example, you're adding only 2.

[Anonymous No.15878168]

>>15877966
>>15877968
>>15877972
You can test latex by clicking on TEX on the top left of the comment box.

[Anonymous No.15878177]

>>15878142
>>15878168
Thank you wise anons

[Anonymous No.15878877]

>>15876111
Just look up the integral for flux and convert it to cylindrical coordinates like the hint says. You can treat the sphere as a point charge if that helps.

[Anonymous No.15878884]

>>15874484
>Any chemist want to explain the actual physics
lol no

[Anonymous No.15879146]

I want to get a secondhand microscope off eBay to see what effect various sharpening techniques have on my knives, what kind of magnification do I need and what brands of microscope are actually good?

[Anonymous No.15879253]

>>15877428
Neat, thanks.