/sci/ - Science & Math

It is known that given a basis, a quadratic form can be expressed:
[eqn]Q(\mathbf{v}) = Q(z_{1}\mathbf{v}_{1} + \dots + z_{n}\mathbf{v}_{n}) = \sum_{i=1}^{p} z_{i}^{2} - \sum_{i=p+1}^{p+q}z_{i}^{2}[/eqn] for [math]p+q \leq n [/math]. How do I show [math]p[/math] and [math]q[/math] are independent of the basis choice? I'm given as a hint to show that [math]p[/math] is the maximum dimension of a subspace of [math]V[/math] on which a positive definite symmetric bilinear form is defined, but I'm not sure how that would help (nor how to do it). I know that if it is positive definite, then [math]p=n[/math], but other than this I'm lost.

>>9570385
Your observation that "deterministic FSA" is redundant is obviously correct, just wanted to highlight that the goal was to construct a DFA.
My problem was with the image I posted under my first post - the exercise is asking to you draw a machine accepting any string not in a*b*, with the alphabet consisting of {a, b}. So the resulting machine will not accept any string including the empty string, correct?
Sorry if my post in the previous thread was a poorly phrased mess.

explain dis

>>9570430
Square

>>9570393
You have one subspace which has dimension [math] n-p [/math] (which one?) on which [math] Q [/math] is negative semidefinite. Now show that any subspace of dimension [math] > p [/math] must intersect that subspace.
On the other hand - the hint already characterizes [math] p [/math] independently of the basis chosen!

>>9570437
>Now show that any subspace of dimension >p must intersect that subspace
h-how?

>>9570450
Assume they don't intersect - what can you say about the sum of the subspaces?

where did I fuck up?

>>9570471
+90 instead if -90 in the third line. You had -((x+9)/12), not (-x+9)/12

>>9570471
should be a negative 90 and a positive 45

In classical mechanics, [math] \dot{x} = \frac{\partial{\mathscr{H}}}{\partial{p}} [/math] and [math] \dot{p} = -\frac{\partial{\mathscr{H}}}{\partial{x}} [/math]. Whereas in quantum mechanics, [math] \displaystyle \dot{\psi} = \frac{H }{ i }\psi [/math], with \hbar as 1.
Purely formally, define [math] H(x, p) \doteq (H_x, H_p) [/math], where the subscripts denote partial derivatives and the ordered pairs are identified with complex numbers. Then the Hamiltonian equations are [math] \dot{(x, p)} = \frac{H}{i}(x, p) [/math], which is essentially the same as the Schrodinger equation. This isn't a coincidence right? I don't have a proper education in physics so please no bully.

I have to show something similar to:
|a+b|-|a|=sign(a)|b|
How do I write it properly?

>>9570497
what do you mean, something similar to

>>9570480
>>9570479
thanks family

>>9570464
What do subspaces have to do with this at all?

When do i use laplace transforms?

>>9570552
DE's

>>9570497
What you posted is not true. Just take a = -2 and b = 5 for example.

>>9570562
well no shit

say i get a list of DEs
just by looking at them, how would i pick out the ones to use laplace transform on?

>>9570482
What exactly is your question?
Of course it's not a coincidence, both derive the time evolution from the total energy of the system

>>9570575
list of common LTs and their inverses

How much programming knowledge is required for computer integrated manufacturing? My school offers a class in it for my Mech program.

>>9570575
when you have the boundary conditions for them and you run out of other ideas on how to solve them.

>>9570501
>>9570568
Aw true that...
But pic related is my problem, isn't is false too then?
The gâteaux operator for a norm is defined as: ||.||' (u,v) = lim (||u+hv||-||u||)/h as h tends to zero

How do you write properly irregular movement's values in english? Let's say a body traveled 50m in 5s and then it traveled 30m more in 15s. Now we need to find V(avg)

So we have t1, t2. How do you properly write final t? Just t or t(avg) = t1+t2?

Find the volume of the solid that is generated when the region is revolved as described.
The region bounded by [math]f(x)=\sin{x}[/math] and the x-axis on [math][0,\pi][/math] is revolved about the y-axis.

I used the shell method so that
[math]2\pi \int_{0}^{\pi}\sin{x}\,dx[/math]
[math]=-2\pi(\cos{\pi}-\cos{0})[/math]
[math]=4\pi[/math]
But I'm told the answer was [math]2\pi^2[/math], what did I do wrong?

>>9570639
>what did I do wrong?
that's not the shell method, needs to be x*f(x)dx

>>9570662
Thanks, can't believe I didn't catch that

So if we take an abstract body moving with constant speed and over all possible observable time speed does not change i.e. there are no other bodies affecting it - the said body technically in the state of inertia? Like, for example, a sattelite? Or does gravitation of the earth affects its inertia state?

Is a professor allowed to cancel a lecture in order to attend a conference?

What is the soul? What makes me I?

If I have a number, and at least half of it was erased
How do I find the whole number (lowest possible), knowing that it was the result of 2 to the N-th power, knowing that n is a positive integer?

For example, if the given number is 1, i want 128

>>9570715
if you were a professor, would you?

>>9570812
>How do I find the whole number (lowest possible), knowing that it was the result of 2 to the N-th power, knowing that n is a positive integer?
You can't.

>>9570715
Typically you arrange for someone to cover for you in that situation.

Hey can someone help me with understanding blood pressure. I was confused until I recently just had a moment and I think I understand blood pressure.

So blood pressure is the pressure of circulating blood on the walls of blood vessels. If we imagine a tube that is 1m and we pinch (vasoconstriction) at 50cm in, then upstream of the constriction (before the constriction) will have an increase in blood pressure since there is more blood there (decreased blood flow as we are constricting). But after the constriction point, downstream, we will have a decrease in blood pressure since there's less blood there (so less blood is hitting the walls of the blood vessels).

The body can change BP by vasoconstrictors and vasodilators (hormones) and nerve innervation.

I also have a q: is BP mainly important because if we have a high BP, then it could potentially burst vessels open since blood builds up and we also strain the heart since more contraction is needed to push the blood through a narrower space. Low BP means that its harder for the blood to go to the organs since there's less of a push/force to move the blood though. So in both high and low BP, the heart works harder to rectify the condition.

I have a = 2.5cm, b= 1 cm, c= 0.7cm and mass is 0.32g
I need to find p (density)
My solution is 0.32g/1.74cm3 which is 0.18g/cm3 yet the answer says it should be 1.8g/cm3

where did I fuck up?

>>9570854
m/v = 0.32g /( 2.5cm * 1 cm * 0.7cm) = 0.18g/cm^3

>>9570865
Yeah, that's my solution which is wrong because answer is 1.8g/cm3
Which does make sense, since it is sugar but then the mass make no sense, it could not be 0.32g, has to be 320g or 0.32kg

I'm right or missed something important?

>>9570871
The answer is wrong.

If I wanted to find the average position of a function
[math]s(t)=6e^{-t} \sin{t}[/math]
on the interval [math][0,2\pi][/math]
Would I do
[math]\frac {\int_{0}^{2\pi}6e^{-t} \sin{t}\,dt}{2\pi}[/math]

Why does the existence a basis [math] B = \{ \alpha_1, \alpha_2,...,\alpha_n \} [/math] with [math] T \alpha_i \in \mathrm{Span}(\alpha_1,...,\alpha_i) [/math] guarantee that [math] T [/math] is triangulable? I'm currently reading page 203 of Hoffman & Kunze and I understand the construction of this basis, I just don't get why the matrix [math] T [/math] is necessarily triangular with respect to it. Any help would be much appreciated.

>>9570854
Go over the units again in your book

>>9571011
Have you tried writing out the matrix? It follows immediately from the condition you're given

>>9571034

Anyone?

>>9571037
Got it, I feel pretty stupid now. Thanks for the reply.

what happens on the last line? the transpose seems to be done entrywise
why is it not [math](A^T,-A^T,I)^Tz=\begin{pmatrix}A^T\\-A^T\\I\end{pmatrix}z[/math]?

>>9570594
This.

>>9570575
It's basically to reduce the order and turn a calculus problem into an algebra problem if you have a table of common Laplace transforms with you. If you do it by hand, then inverse Laplace transforms only turn the calculus problem into a complex analysis problem and you have a nasty cauchy integral to deal with. If you have conditions of the original function and you do not want to or can't use other methods of solving the differential equation, then you use Laplace transforms.

>>9570429
> My problem was with the image I posted under my first post - the exercise is asking to you draw a machine accepting any string not in a*b*, with the alphabet consisting of {a, b}. So the resulting machine will not accept any string including the empty string, correct?
It will reject any string consisting of zero or more "a"s followed by zero or more "b"s. IOW, it will reject:
- the empty string
- any string consisting solely of "a"s
- any string consisting solely of "b"s
- any string consisting of a run of "a"s followed by a run of "b"s.
It will accept anything else; which essentially means any string having "ba" as a substring.

I'm such a goddamn brainlet: I seriously do not fucking understanding radians and degrees. Are they fundamental and unitless like "5" or "7". Or are they units in the same sense meters and Newtons are? If the latter, does that mean e^(pi*i) + 1 = 0 is only true in the units of radians? And, if by convention we used degrees more often, we could claim e^(180*i) + 1 = 0?

What does the less than symbol mean when referring to operator spaces?

So like I've got some hilbert space A and the set of hermitian operators on this space is L(A). In this paper I'm reading there's another operator space S defined on the hilbert space B (which may or may not be equal to A) such that

S < L(A)

What does this mean?

>>9571243
That means they differ by a positive semi-definite self-adjoint operator that is not zero.
That is, a > b, if and only of a-b is a nonzero element of the positive cone of L(A).

>>9571243
>>9571264
Ok, forget about that, I misunderstood your question. Probably it is some embedding relation?

>>9571243
>>9571271
Just realised I misread something in the paper, the operator space S actually is defined on the hilbert space A.

With that being the case what does an inequality between operator spaces on a hilbert space mean?

>>9571316
I understand that for individual operators an inequality A<B means that the eigenvalues of (B-A) are positive if that makes explaining any easier.

>>9571243
subspace?

How would I prove b) here? W is supposed to denote the domain of the function/program. Really have no idea how I'm supposed to use the hint

Can someone help me with indifference curves? How can you have multiple of them?

chem questions, would appreciate any portion of input you can give
1: How could you identify a sample of cyclohexene?
I have written down "weigh out known volume of liquid and compare to density of cyclohexene (0.811g/ml)". What other test could say to make this answer more complete?
2.(long) Show all the structures of the possible acid-catalysed dehydration products of the following:
i)Cyclopentanol
ii) 2-Butanol
iii) 1-Methylcyclopentanol
If more than one alkene is possible, predict which one will be in the largest amount.
3. What is the major disadvantage of using concentrated sulfuric acid instead of 85% phosphoric acid as a reagent in the dehydration of an alcohol?

>>9571444
Forgot my answers for 2 and 3, and writing them now they look complete
2.
a) Cyclopentene
b)Trans-2-butene (largest amount)
1-butene
Cis-2-butene
c)1-methyl-1-cyclohexene (largest amount)
Methylenecyclohexane
I think I got them all
3.
sulfuric acid is an oxidizing agent and can oxidize the alcohol to form other products (sulphur dioxide, carbon dioxide)

>>9571438
I'm not entirely sure what you're asking.

There are multiple indifference curves because each one maps a set of bundles that gives the same utility and a higher curve represents higher utility. So for example, any point on I3 has the same utility but any point on I3 gives a higher utility than every point on I2.

The budget constraint is used to see what affordable bundle gives you highest utility. This is usually found on a utility curve that runs tangent to the budget constraint.

>>9571470
>any point on I3 has the same utility but any point on I3 gives a higher utility than every point on I2.
sorry, let me reword this: all points on I3 give Kevin the same utility but any point on I3 gives Kevin a higher utility than any point on I2 would give him.

>>9571471
So anything above the budget constraint would be a utility not achievable?

>>9571481
Yeah. Basically in these questions you're just always looking for the highest curve that is still touching the budget line.

are quadratics the first mong filter

Is Econometrics really a good course for getting hired?

What's on the blackboard? It's definitely physlcs... EM?

>>9571525
Similarly here.

>>9571525
Looks like utter nonsense.

>>9571525
On closer inspection, this one isn't physics, but >>9571528 absolutely is.

I took Diff Eq the summer of my freshman year and I am now in grad school, where I find myself using it constantly. Long story short, I had a shitty professor but still did fine in the class but I didn't come away with much. I want to actually understand the more complex shit so I can understand and solve harder problems.

Any recommended books for refreshing knowledge/learning more? Please and thank you anons.

Does [math]Int(\overline{A}-A)=\emptyset[/math] always happens in the topo0logy of a metric space? Can't find counterexamples, but I can't prove it either

>>9571240
Angles are unitless; they're ratios of lengths. One radian is one metre of arc length per metre of radius, or one foot of arc length per foot of radius, etc.

>>9571381
I believe this is it, though it's been a while.
[math]e \in \texttt{Tot}\leftrightarrow W_e=\omega \leftrightarrow (x,e)\in \{(x,y)~|~W_x=W_y\}.[/math]

>>9571528
Looks like cylindrical or spherical capacitor or something like that.

>>9571525
>>9571528
See you in 2 days barneyfag

Since the region isn't closed, Green's theorem gives you 0. I know the answer is 20, because you have to include the distance from (0, 10) to (0, -10). You only get 20 if you go from bottom to top; if you go from top to bottom, you get -20. My question is, Does it have to be done in a certain direction? Is there a way to end up with +20, if I go from top to bottom?

>>9571809
FUCK
ME

>[math]x = A e^{st}[/math]
>if s may have 2 values, [math]x = A e^{s_1 t} + B e^{s_2 t}[/math]
why?

>>9571851
What exactly is your question?

>>9571860
why is that statement true? I feel like it's some basic algebra but I can't figure it out

>>9571881
>why is that statement true?
What is the context? "if s may have 2 values" is a meaningless notion.

>>9571888

>>9571851
>>9571894
that's just the superposition principle

>>9571543
anyone?

>>9571851
s gets 2 values from assuming a differential equation has an exponential form (how you solve every differential equation) then solving for the coefficient in the exponent

other than that i think there's a linear algebra reason for it having two exponentials in its solution. probs something to do with the eigenvalues and probs 2 derivatives

are there any infographics out there showing all human spaceflight orbits done up to today?

>>9570715
depends on the school but generally i'd assume yes, as long as you do a makeup class or have someone fill in for the lecture. i had professors do this occasionally in classes

>>9570387
can someone show me the proof of lagrange error bound? prof did a shitty job of explaining it.

Best books regarding linear algebra / diff. eq.?

>>9571543
How about Schaum's Outline series? Cheap and to the point with several practice problems with solutions.

If I put the neck of a whiskey bottle (assume 40%abv) up my ass and do a handstand for ten seconds, am I likely to die of alcohol poisoning?

If I put the neck of a whiskey bottle (assume 40% abv) up my ass and do a handstand for ten seconds, am I likely to die of alcohol poisoning?

To any LaTeX whiz:
Why is there no table of contents showing up?

I clearly have several sections and subsections, but for some reason they just aren't appearing after I call \tableofcontents
(Pastebin: https://pastebin.com/pvqkTRyh))

I want to start learning differential geometry. Can someone recommend me a good book to start with?

>>9572143
section* -> section

>>9572050
I'll check it out, thanks anon

>>9572148
Funny you mention this. I was in a really similar boat up to a few weeks ago.

I very highly recommend Kreyzig's "Differential Geometry" text.
I'm going through it rather slowly, but at least up to describing surfaces the explains a lot of important formulas pretty well. They have a lot of interesting problems (and thankfully very detailed answers for the problems), so you'll get a lot of interaction with both theory and practice.
https://books.google.com/books/about/Differential_Geometry.html?id=P73DrhE9F0QC

>>9572156
Gotcha... I'm personally not a huge fan of having the numbers, but removing the asterisk works, so I'll have to make do.

>>9570808

>What is the soul?
There isn't one.

>What makes me I?
The consciousness you have is from your brain chemistry and sensory system. Living things need senses to interact with their environment and to process the information a brain system develops. That's all your conciseness is.

>>9572166
Yeah, I was looking into learning a little bit of differential geometry because I'm thinking about take a course about that in my next semester. Thanks for the recommendation, senpai.

>>9572179
Spivak volumes 1-5
Gerald Jay Sussman, Jack Wisdom, Will Farr-Functional Differential Geometry

>>9572148
surfaces or manifolds?

>>9571381
Note that N is the domain of f(x) = 1, and f(x) = 1 is computable. Therefore, We = N for some e.
Thus, Wx = Wy is decidable -> Wx = We is decidable -> Wx = N is decidable -> Phi x is total is decidable.
This is a contradiction, so Wx = Wy is not decidable.
This is what it means to reduce a predicate A to another predicate B. You show that B is decidable -> A is decidable, and if A is undecidable, then B can't be decidable. So A is reduced to B.

>>9572180
I'll look those too, thanks!

>>9572188
I'm not sure about what the course I'm getting into is going to focus on, but I'm interested in manifolds.

https://www.sciencedirect.com/science/article/pii/S0166864115001273
What the fuck does this shit mean?

>>9572205
Do you have a more specific question?

>>9572208
I looked up some of my professors research. I don't understand basically any of what this is, other than that it's about topology.

>>9572180
>Gerald Jay Sussman
Huh, that's the same guy as the SICP lectures... Didn't know he worked on Differential Geometry.
That's pretty neat

>>9572214
Have you tried asking him?
At least in my experiences, professors tend to rather enjoy explaining their research to students
At the very least, ask him to point you in the direction of materials that will help you understand his research more.
But what do I know?

>>9570846
BP is regulated across the entire vascular system, so it isn't so much a local pinch as it is a total peripheral increase or reduction in pressure due to increased or decreased peripheral tension.

In terms of pathologies of high or low BP, low BP is obviously bad due to a decreased oxygen supply and prolonged high BP can lead to endothelial dysfunction, which can lead to atherosclerosis.

Studies hypertension for half a year so ik no expert but it is the biggest contributor (risk factor) for global mortality

>>9571753
Thanks, anon.

>>9570578
I guess I was asking if there was a way to make that "derivation" I wrote more rigorous.

Why doesn't a black hole increase in size?

>>9572403
They can. Just add more mass.

What is the point of doing anything when the ultimate fate of all life is extinction, and the universe will just end up a cold, dark, near-empty (except for low-energy photons and neutrinos), lifeless abyss?

>>9572523
Because you want to.

>take an antibiotic for stye
>asthma goes away for a week
how
Also when's the fucking asthma cure coming

do the ten or eleven systems (some combine things like the male and female reproductive systems) of the human body account for everything that's going on inside it, besides bacteria and things like that?

>>9572593
Disclaimer: I'm a non-expert. But I would say no. Take the eyeballs for example (eg. lens, rod and cone cells, vitreous humour). Or the workings of the inner ear (eg. cochlea, semicircular canals). So far as I know, they don't fit under any of those 11 categories.

Getting 14.5 while answer is 13.5 wtf?
my final calculation was:

[math]\frac{87}{8} - \frac{4}{3}[/math]

>>9572570
Maybe you had a minor lower respiratory infection exacerbating your asthma just prior to taking the antibiotics, who knows.

>>9572669
I also got 14.5, and so did my calculator

>>9572696
Thanks gotta be error on their end then

What calculator do you use to calc fractions? Or wolfram understands TeX?

>>9572714
>>9572696
nevermind WA is retarded:
https://www.wolframalpha.com/input/?i=87%2F8-4%2F3

so i'm trying to study with someone who is taking differential equations and it turns out their calculus knowledge is bolted together entirely from mnemonics that have managed to put-put them along through passing calculus classes

i figured this out when they were trying to figure out how to exponentiate out a logarithm and did something i've never seen so illogical before.

anyway, i need something recommendations for books like gelfand's 'trigonometry' but for pre-calculus topics: essentially just a tome of practice problems so we can sit and drill logarithms and other such stuff because while i can notice what they're doing wrong and teach what must be missing in order to correct it, i can't actually myself write out a lesson plan of how to relearn all this basic stuff.

please rec me such books.

>>9572722
https://www.wolframalpha.com/input/?i=(15+-+33%2F8)*(59%2F15+-+13%2F5)

>>9572714
>What calculator do you use
I just used a regular calculator with decimal points to double check my answer. It said 14.5 as well. Yeah, error on their end.

Correct me if I;m wrong but 2 balls colliding, one is 1kg and 2nd one is 2kg, the small one repels back at 2m/s then the big one will have Vsmall/2 speed right? So 1m/s?

I have to explain what happens when this code is run (Python 3) and why.

I understand that the function takes a variable v and inserts it into a list at the start and can explain all the steps apart from the last one. Why is it that [7] gets inserted into the list containing the 5 from the first call of the function? (i.e. you get [ [7] , 5] )

I can backwards rationalise it as the fcn creates a default empty list that it uses in the absence of an argument but I dont know enough about Python memory management to know if this is true? I also dont understand why it would do that in the first place. Is it because python is based on C/C++ and you need to manually dealloc your heap memory? Is it to do with python garbage collection?

>>9572912
Two things:
1) Holy shit, what is this? a picture for ants?
2)Okay, so a way to solve these problems usually is to type it up yourself and experiment.

When I typed up the code, I wanted to make sure the behavior we see extends to more than just the two function calls you're referring to. I did this by calling the function a couple of more times with different arguments an seeing the result (see picture).

As you can see, for some reason, the "list" variable doesn't get reset between function calls.
Looking this up, we see here:
http://docs.python-guide.org/en/latest/writing/gotchas/
that not only is it expected behavior, it's encouraged in some situations.

This doesn't really have anything to do with heap allocation (python is too high level to worry about that, much to my annoyance), so basically the reason it does this is "it was designed that way" but if you want to be more specific, just say "default arguments are evaluated at the time a function is defined, not when you run the function"

>>9572879
Conservation of momentum:
[math]
v_1 m_1 = v_2 m_2
v_2 = v_1 \cdot \frac{m_1}{m_2}
v_2 = 2 \cdot \frac{1}{2}
v_2 = 1m/s
[/math]

>>9572930
My bad, didn't format correctly
[math]
v_1m_1=v_2m_2\\
v_2=v_1⋅\frac{m_1}{m_2}\\
v_2=2⋅\frac{1}{2}\\
v2=1m/s
[/math]

>>9572912
>I also dont understand why it would do that in the first place.
This is a specific example of the general case that Python is a very bad language and an extremely bad first language. It makes a host of very strange decisions which mangle syntax and semantics on behalf of programmers.

The answer to the question "Why does Python do it this way?" is "Because they said so fuck you." Why doesn't Python allow tail call elimination? Because fuck you. Why does python have magic names? Because fuck you. Why does python overload addition on random shit? Because fuck you.

It's a better Perl. That is all it aspired to and that's all it got. The specific bromide is "damning with faint praise."

>>9572930

TYVM! Guess my gut instinct was right. Yeah I'd done that but basically was at a loss as to what to look up to check and find out.

>python is too high level
Yeah I supose, I just jumped to that since it's mainly actually cal using the CPython interpreter and the closest thing I could think of was issues with 'new' variables

>>9572937
Yeah I much prefer C++/C even though I haven't used them in a while because I 'know' what's going on at every step and strict typing makes everything more clear. Had a friend who had a 3-4 week roadblock in her phys masters project because she'd accidentally put a =+ instead of a += and Python had just decided that was fine and did something different with it w/o throwing an error

>>9572932
so it is always a half of the speed right (when talking about body with smaller mass:body with larger mass, obviously it will be 2x more vice versa)?
or there are cases when it is not?

Can someone suggest some books on understanding probability or a general path of maths to learn to understand statistics?

>>9572964
>she'd accidentally put a =+ instead of a += and Python had just decided that was fine
jesus that's disgusting

>>9572998
If Jupiter's mass is 317,8xM(earth) then why is Jupiter's g = 2,535 and not 317,8*9.8?

Do I have to take into account radius?

>>9573018
jupiter is much less dense than earth and gravity falls off with the square of distance

HELLO.
I REQUEST HELP.

SO IF I AM MAKING A ASSIGNMENT/LIST AND I AM STRUGGLING TO DO 1 OF THE QUESTIONS.

DO I INSIST AND RESEARCH THE SUBJECT OF THE QUESTION OR DO I SKIP IT AND GO TO THE NEXT ONE [WHAT IF I DONT KNOW THE NEXT ONE, DO I SKIP IT AS WELL?].

1-HOW DO YOU PERSONALLY DO IT?
2-DID YOU EVER DO IT THAT WAY?

THANK. YOU.

>>9573024
I'm not talking about planetary gravity. I mean: but on it's surface, 1:1, a body of 10kg mass should be still affected by full gravforce. But fomr some reason it is way less

>>9573030
Depends on how much time you have.

>>9573043
>But fomr some reason it is way less
jupiter is much less dense than earth and gravity falls off with the square of the distance

>>9573056
>>9573024
What the point of your presence in this thread? Re-read the OP and consider ctrl+W

>>9573043
Jupiter's surface is much farther away from its center of gravity than earth's surface is, thus the gravity on the surface is less than if it was the same distance.
Jupiter isn't heavy enough to counteract this increased distance when compared to Earth.

>>9573061
thanks senpai
so in other words I needed to take into account radius as I thought

where the fuck is the laplace symbol in texlive (texstudio)

>>9573045
EITHER WAY I JUST WANT TO LEARN.
I BELIEVE THE LOGIC HERE IS "SALVAGE WHATEVER QUESTIONS YOU CAN, THEN" UNDER THE ASSUMPTION ONE QUESTION OR ANOTHER WILL BE LEFT UNANSWERED?

FOR SAKE OF THE QUESTION, LET'S ASSUME WE HAVE OPTIMAL TIME, WHATEVER THAT IS, OR SUBOPTIMAL TIME.

WHICH IS BETTER FOR OPTIMAL TIME?
WHICH IS BETTER FOR PEOPLE WITH LESS TIME?

>>9573068
If there's a question you don't get, look at the other ones first, if you have to do them or they aren't totally trivial and you aren't 100% confident about being able to solve them, do them, then go back to the questions you couldn't handle.
This is how you do exams and self study as well, makes sure you actually get shit done and not just exhaust yourself without doing anything. That's how I do it, anyway, to be honest I don't practice much so this might be suboptimal advice.

What's up my dudes, can anyone explain to me why the limits of integration for the right half of the cardioid r = 4+ 3sin(theta) are -pi/2 to pi/2 instead of 3pi/2 to pi/2?

>>9573119
pi/2 to 3pi/2 is the left half bro it's widdershins m8 and if you make it 3pi/2 to pi/2 it's fucking still fucked but now its negative fucked you feel me

Any lads able to help me with this genetics question?

I found the answer on chegg, but I still don't understand.

To any numerical method person:

I'm reading several texts that mention solving systems of linear equations.
IF I understand this right, both LU-Decomposition and Gaussian elimination require O(n^3) operations to perform, with LU being slightly more efficient, but the following two passages confuse me:

"Gauss-Jordan elimination has the disadvantage that all right-hand sides must be known in advance. The LU decomposition method does not have this deficiency... With LU decomposition, we can solve with as many RHS as we need to, one at a time."

How is this different from teh Gaussian elimination/Gauss-Jordan method? We need to know the RHS for both of them, don't we?

Another question: Is there a case where we would use QR factorization over LU factorization?

>>9573076
THANKS. I THINK THE KEYPOINT THERE IS MINIMIZING ERROR OF IDLENESS, I COMPLETELY AGREE WITH THAT LOGIC.
I WILL TRY YOUR ADVICE.

>>9573281
it seems weird to me as the relationship between LUP and GJ is pretty straightfoward

I guess they are thinking about using GJ to solve the system via an augmented matrix and row operations while looking at LUP as a matrix factoring algorithm which doesn't require a RHS at all.

sort of like solving ax^2 + bx + c = N versus factoring a quadratic (not caring about what it equals at all)

seems like a very fine point to me

I don't know shit about QR sorry

Where can I find a college mathematics textbook to study for this CLEP test I scheduled for next Wednesday? I dropped outta high school in 10th grade so I don't know shit beyond acute triangles and the order of operations.

>>9570387
>Be me
>mom calls
>Hey anon can u help ur lil sis with her math bullshit because she is going to middle school?
>k.
>helping
>challengerAppears.gif
I literally tried to do this for 2 hours and I couldn't.
This is supposed to be done by 14-15yo children.
I am ashamed of myself.
Please help me anons.

The answer is 18Pi

>>9573404
Forgot to post problem I am automatically posting anime girls without thinking.

>>9570635
For h small enough u+hv and u will have the same sign.

>>9573404
>>9573406
insufficient information, there is infinite number of such inscribed circle pairs such that AB = 12

Do you lose mass when you take a shit?

>>9573419
When I tried I got about 3 different values of the final area but the book stills says 18Pi and I am pretty sure the problem was already solved in her school because there are scribbles in the book

>>9573434
depend what you mean by "you"

>>9573447
Does your body lose mass after taking a shit?

>>9573457
If you consider your shit part of your body.

>>9572912
The definition specifies that the default value for the "lst" parameter is an empty list. A *specific* empty list, created when the function is defined. Whenever the function is called with one argument, the "lst" parameter will be that particular list object.

This is a fairly well-known issue, and easy to avoid once you know about it (just change the default value to None, and have "if lst is None: lst=[]" inside the function body). The official Python tutorial flags it (see "Important warning" in bold type):
https://docs.python.org/3/tutorial/controlflow.html#default-argument-values

The alternative would be for the function's definition to store the expression, and evaluate it whenever the function was called without an argument for the "lst" parameter. But that's not what Python does. Apart from being more complex to implement, that approach will also have "gotchas", and some of them would probably be worse than the one you encountered (e.g. what would be the scope in that situation?).

Note that C++ does the latter (i.e. the expression is substituted into each call where the argument is omitted). But C++ is already so complex that one more complication hardly matters.

>>9571444
1. IR spectroscopy, NMR, Mass Spectrometry, XRD, testing of freezing point and boiling point

>>9573444
I don't doubt that there is a solution, but you need to post /all/ of the information contained in the original problem statement.

If there is a series of problems, some of the information may be stated in an earlier problem and it's implied that it applies to later problems.

>>9573481
Half circle, |AB| touches the small circle C where they meet |AB| = 12cm. literally 2 sentences + "What is the area of the blue part (in my case)"

>>9573488
it is not possible to solve with info given as for every outer circle of diameter larger than 12 there is such an inner circle with such a chord

you need more information, period

which are the best algebra & trig to start with?

no memes

>>9573187
So I can use -3pi/2 to pi/2 or -pi/2 to pi/2 correct? Anyways thanks, scottish? anon for reminding me about the direction of polar coordinates it helped a lot.

>>9571444
>>9571460
2. These are all correct. In carbohydrate intermediates, the carbocation will only move to the carbon with the fewest hydrogens (major product) or next to the carbon with the fewest hydrogens (minor product).
3. Also correct, phosphorus is more stable while bonded to oxygen because the bonds are more polar compared to sulfur (due to electronegativity).

>>9573577
>the carbocation will only move to the carbon with the fewest hydrogens (major product) or next to the carbon with the fewest hydrogens (minor product)

I also want to add that the carbocation can move even further away than the carbon next to the carbon with the fewest hydrogens if the reaction takes place at very low temperatures.

Trying to understand principle of explosion

given, for example,
[math]2+2 = 3[/math] and [math]2+2 = 4[/math] as true, how can i prove that [math]a^{2}+b^{2} = (a+b)^{2}[/math]?

>>9573406
>>9573404
Where do you live?

>>9573616
Czech why?

>>9573590
From 2+2=3 and 2+2=4 you can "prove" that 3=4, and from there that 0=1.
(a+b)^2 = a^2+2ab+b^2
= a^2+1*2ab+b^2
= a^2+0*2ab+b^2 (because 0=1)
= a^2+b^2

If you can prove that any two different numbers are equal, you can use basic arithmetic to prove that any two numbers are equal. Once you have 0=1 you have 0*a+1*b=1*a+0*b => a=b for any a, b.

Someone plug this into their calculator. I keep getting a different answer

>>9573705
My book is also giving a different answer, which is weird. The equation should given in the picture be correct.

So I made some nickel acetate for electroplating.
Its just 5% acidity vinegar, pinch of salt, pure nickel that had electricity blown through it.

I know im a pussy, but how exactly am I supposed to handle it and what sort of precautions should I take?

What exactly did the nickel do to the vinegar, and how much more dangerous is it now?
Other acetate tutorials use much stronger acids like sulfuric acid so this is supposed to be safer but im still apprehensive to play with it.

Guys how the fuck do I learn circuits? I'm taking Circuit Theory and I feel like a total dumbass. I even struggle with finding total resistance, not to mention stuff like Thevenin's theorem and RLC circuits in general.

are dot product and cross product a definition? I cant wrap my head around what they fuck they _actually_ are, seems completely arbitrary to me.

>>9573815
is addition a definition?

>>9573833
yea, i would consider it a definition, but i can see what the fuck they are doing, i have 2 and 2 apple, so they are both 4. but a 2 dot product 2 is doing what exactly?

>>9573841
Well 2 dot 2 is just multiplication. Otherwise project the first vector onto the second and scale it by the magnitude of the second vector.

>>9573202
So if the codons mutate what happens? They are now stop codes and won't be read to stop the synthesization so Tryptophan will keep being produced if it is present. It it isn't it will not.

At least that is what I think it is but do not take my word for it.

i am literally too fucking retarded for electrostatic calculus, jesus christ why do i have such a brainlet brain?

> If f (x, y,z) is a continuously differentiable scalar function, show that ∇ × (∇ f ) = 0.
can someone explain the significance, it is not apparent to me why this is the case. I get the proof that achieve this result but I don't see what the significance of this result is.

>>9571438
indifference curves are like a topological map of the utility function. if you graphed the utility function as a function of two variable it would be in three dimensions and look somehow mound shaped. the indifference curves trace out points along the mound that have the same height. height in this context is utility, so that is why we call them indifference curves. a consumer is in theory indifferent between bundles of goods that provide equal utility.

>>9571042
just read page 12 and on in this it will explain it better and with an example than I could.
ftp://140.131.110.38/lfchang/public/FE%20TOPICS/Ch2.pdf

Brainlet here, trying to (re-)learn some very basic algebra.

The problem is to factorise pq+12qr. I thought it was q(p+12r). Wolframalpha says I'm wrong and it hasn't let me down before, but I honestly can't see what the issue is.

>>9574062
>I thought it was q(p+12r).
It is. Wolfram fucked up.

>>9574069
Thanks anon, kind of weird that it'd get this wrong seeing as it can handle some seriously complex queries.

>>9574078
Yeah, I'm not sure why it gets this wrong either. It even describes an "alternative form" of your question as "is q(p+12r) = q(p+12r)", which is unmistakably the case. Weird software be weird.

>>9570518
The exercise connects the index of a quadratic form with subspaces of the respective vector space... You should be familiar with subspaces when doing linear algebra...

>>9574096
More weirdness: What I actually typed was
>is pq+12qr equivalent to q(p+12r)
If I retype exactly the "input" that it shows in my first screenshot, spaces and all, it gets it right.

>>9574104
you're supposed to be explicit with multiplication of variables I bet

>>9574104
Oh -- I suspect it is interpreting "pq" as a single variable, not shorthand for "p * q"; whereas "p q" IS interpreted as "p * q". In other words, don't skimp on those spaces :)

>>9574118
>>9574125
Gotcha, that works

i'm the best student in my math class and i'm a complete retard
is this what it feels like to be smart

>>9570430
its quadratic because you have 4 terms dumbass

>>9570552
I'd like to laplace my transforms in her

Where is the most "mild" place on earth in terms of climate? Warmest winters and coolest summers, least variance and sitting around 20-25C all year long?

>>9573781
>How do I learn circuits?
Dude if I knew I would totally tell ya.

The most advice I could give you is to read through a textbook. A really good one I've found is "Hughes Electronics Engineering"

I'm taking a circuits class right now and a lot of it is just gaining the intuition to solve more complex problems.
For example, I recommend you really drill into your brain the voltage division equation (R2/(R1+R2)) because once you move on to impedances (resistance for non-resistor elements like inductors), a lot of the same theorems apply

For RLC Circuits, if you're not really being asked to draw out exactly how it behaves, just think about what its behavior is at DC after a long period of time.
A capacitor acts suspiciously like an open circuit after a long time (we find this is the case because its impedance is proportional to the reciprocal of frequency, and 1/0 -> infinity)
An inductor acts suspiciously like a wire after a long time.

Once you know those two, you can start making more and more sense of the circuits you're given. If you're ever stuck, just handle it one component/node at a time

Good luck, mate!

Not sure if im retarded but cant figure this out.

I can do regular linear programming stuff with 2 variables however this question seems backwards as it is asking for an objective function and it has 3 decision variables which is confusing me.

What should be the thought process here? I can't think of how I should be making the objective function.
Since [math]x + y + 2z \leq 1[/math] is a plane so if the objective function intersects it it would make a line. But even then I'm kind of confused

Some sources define the Turing machine transition function as δ: Q x Γ → Q x Γ x {L, R}, and others as δ: Q x Γ → Q x Γ x {L, R, S}. Why does one consider the "stay" move S, and the other doesn't? How crucial of a difference is this?

>>9574786
Never mind, the one with S is defined for multi-tape Turing machines.

>>9574344
Thanks anon, already have a textbook but it's going way too fast for me so I'll check the one you recommend. The good part is that I can see how solving circuits could be pretty fun and challenging, but my brain just hates to retain this kind of information.

If you dug a hole from one end of the earth to the other that was just wide enough for you to fit through, and you jumped down it feet first, would you come out the other side feet first?

>>9574823
Is the hole through the center? Ignore the whole "you will burn within the melted core" you probably would stuck weightless in the center

>>9574440
First, linear programming can have any number of variables. Real-world problems may have 100,000 variables. 2-variable problems are often used to explain basic concepts because they're easy to draw.

The constraints in this problem give you a tetrahedron bounded by four planes: x=0, y=0, z=0, x+y+2z=1.

The dimensionality of the solution set is determined by the number planes on which the solution set lies. Three variables form a three-dimensional space; each plane reduces the dimensionality by one.

a), requires that the solution lies on the intersection of 3 planes, b) on 2, c) on 1.

If the constraints are all expressed as cx*x+cy*y+cz*z<=k, then maximising an objective function f(x,y,z)=ax*x+ay*b+az*z will yield the set of points corresponding to the intersection of all planes for which the dot product of (ax,ay,az) and (cx,cy,cz) is zero or positive (for minimising, it will be zero or negative).

So choose 1, 2 or 3 constraints, then find an objective function which has the correct signs for all 4 constraints. I.e. the "axis" along which the objective function increases (or decreases) needs to point toward one corner/edge/face and either away from or parallel to all of the others.

How do I construct a bijection? I don't know where to start with

Let's say I have linear equation:

[math]\frac{x+7}{3} = \frac{2x+3}{5}[/math]

Now, we move the right part to the left:

[math]\frac{x+7}{3} - \frac{2x+3}{5}= 0 [/math]

now we find common denominator:
[math]\frac{5*x+5*7 - 5*2x+5*3}{15}= 0 [/math]

Why is it wrong?

>>9575048
If they're equal to each other, we cross multiply for:

5x+35=6x+9

Subtract 5x from both sides, and 9 from both sides:

26=x

Plug in to check:

(26+7)/3=11

2*26=52

(52+3)/5=11

x=26

>>9575048
you should have -5*2x-5*3 in numerator

>>9575056
>you should have -5*2x-5*3 in numerator
Yeah, why is that?

I understand that is basically this

[math]1(2+3)-5(3+4) = +1*2+1*3 - 5 *3 + (-5*4)[/math]

Just having issues wrapping my head around it when comes to fractions

>>9573406
Assuming both of their centers are on the line going through C, and you know R the radius of the larger circle, from AB you can calculate the height of the AB line, which gives you the radius of the smaller circle. Subtract the area of the smaller circle from the area of the larger and divide by 2.

>>9573493
I haven't checked but it's possible that the answer is the same regardless of the radius. Unlikely, but possible.
>>9575105
In fact let's just [math]2A=A_R-A_r=\pi R^2-\pi r^2=\pi R^2-\pi (R^2-6^2)=36\pi[/math], so [math]A=18\pi[/math], which is indeed independent of the radius of the larger circle.
This is assuming the segment between the two centers is parallel to [math]AB[/math].

>>9575111
Where in the fuck 6 came from

>>9575118
12/2

Question is on the post-it in pic-related. Need help understanding the bottom two molecular orbital's energy levels and why e' doesn't decrease in energy relative to it's atomic orbital but a1' does.

>>9575111
>>9575120
And where in the fuck Ar chord came from?

>>9575123
Full diagram as a reference.

>>9573061
>>9573062
Still here?
I'm trying to calculate it using

[math]F_g = G \frac{Mm}{R^2}[/math]

where:
m = 10kg (9.8kg)
M = 1.8982×10^27 kg
[math]R^2[/math] = (69 911 km * 1000)^2
G = grav constant (kg*s*m)

Result is:
https://www.wolframalpha.com/input/?i=(6.674*10^-11)+*+((9.8+*+(1.8982×10^27))%2F69911000^2)

Where did I fuck up?

>>9575130
What do you mean?

>>9575183
I see chord AB
I dont see any other chord in small circle

Post all data that is given fag

>>9575048
because u did [math] \frac{x+7}{3}-\frac{2x+3}{5}=5\frac{x+7}{5\cdot 3}-5\frac{2x+3}{5\cdot 5=15???} [/math], you messed up in step 3, do it slower.

>>9575188
Fine
Based on the way the drawing in >>9573406 looks, I assume
>The radius of the larger circle is [math]R\leq6[/math], radius of the smaller is [math]r[/math], their centers are [math]C_R[/math] and [math]C_r[/math] respectively, the smaller circle is fully contained in the larger one
>[math]CC_R[/math] and [math]CC_r[/math] are parallel to [math]AB[/math]
Then, [math]d(AB,C_R)=\sqrt{R^2-(12/2)^2}=d(AB,C_r)=r[/math].
The area we're looking for is [math]A=\frac{A_R-A_r}{2}=\frac{\pi}{2}(R^2-r^2)=\frac{\pi}{2}(R^2-\sqrt{R^2-6^2}^2)=\frac{\pi}{2}(R^2-R^2+6^2)=\frac{36\pi}{2}=18\pi[/math].
I made these assumptions because I don't see how else OP's problem could be solved.

Does anyone know how to solve [math] y''=\frac{1}{y^2} [\math] ?

>>9575252
https://math.stackexchange.com/questions/2406683/how-to-solve-y-frac12y2

I realise this is probably obvious to most people but I'm still studying for my GCSEs so...

Can anyone explain me this:
The ratio (y+x) : (y-x) is equivalent to k : 1

Show that y = x(k+1) / k-1

>>9575264
Just take x(k+1) / k-1 and substitute k = (y+x)/(y-x)

>>9575264
The first line means that [math]\frac{y+x}{y-x}=\frac{k}{1}[/math], then by multiplying both sides by [math]y-x[/math], we get [math]y+x=k(y-x)[/math].
If we add [math](-ky-x)[/math] to both sides we get [math](1-k)y=-kx-x=-(k+1)x[/math],
then divide both sides by [math]1-k[/math] to get [math]y=-\frac{k+1}{1-k}x=\frac{k+1}{-(1-k)}x=\frac{k+1}{k-1}x=x\frac{k+1}{k-1}[/math] which is what you were asked to show.

>>9575141
I think I figured it out on my own, tell me if I'm wrong,

A1' and E' both have atomic orbitals for both the central and outer atoms but the 2s A1' and E' orbitals of F are too dissimilar in energy to match the A1' and E' orbitals of B, but the a1' molecular orbital that forms can be partially stabilized by the matching symmetry of B although it doesn't bond to it while the e' orbital molecular orbital cannot since A1' of F's 2s orbital is closer in energy to the 2s orbital of B than the 2s E' orbital of F is to the 2p E' of B so it can be stabilized partially.

>>9575287
Or is it because one comes from a 2s orbital and one comes from a 2p orbital so even though their mulliken symbols are identical symmetries don't match enough to compensate for the energy difference?

>>9575283
is there a typo?

>>9575348
No, I just phrased it awkwardly, that's equivalent to subtracting ky from both sides, then subtracting x from both sides.
It's just grouping the unknown on different sides of the equation.

How are you even supposed to manually find relative error?
(Δx)/x

e= (1,6021892[math]\pm0,0000046[/math])*10^19

How in the fuck do you divide 0,0000046/1,6021892 sanely

>>9575283
>>9575350
what if instead of diving we move (1-k)? How does the sign works here?

[math]
(1-k)y = -(k+1)x[/math]
Let's move (1-k) on the right
[math]
y = \frac{-(k+1)}{-(1-k)}x
[/math]
I'm getting different signs

Would a Black Body make the perfect cloaking device?

>>9570387

How have the planets in the solar system lined up so perfectly? Why isn't there a planet that orbits the sun in a completely different direction/angle?

>>9575371
What exactly do you mean by "move"? Always try to keep in mind exactly what operation you're executing, adding, multiplying, subtracting, dividing, etc.
Do it step by step and write things out.

What kind of life would Titan have, if any?

>>9575400

Much the same as on earth, just much, much bigger.

>going to college soon
>don't really enjoy anything or have any interests
>just want to get a degree and make like 50k a year and have job be not too hard


what degree should I do?

>>9575430
Can't really help you there, my aims were at least 20k a year with no direction and I went into maths, will probably go into financial shit.
I think it's better if you can find something you really enjoy that gives you a strong direction, all I knew is I didn't wanna be poor and kinda liked math.

>>9575439
The problem is I don't really enjoy anything. I like animals and I'd prob like a job related to them but those are basically impossible to get.

>>9575430
CS or stats and become an actuary

>>9575383
No, because you wouldn't see anything behind it, you retard.

/agdg/ here
I'm learning basic math to make statistics and damage formulas for my game.
What I heard is that I need to learn the subject: formulas and graphs.
Right now I'm learning from mathisfun's algebra section starting from top to bottom (basics of algebra to functions and sequences), as well as peeking into what functions are like (whether that be on mathisfun or another site that I found via google).

The lessons are easy to understand and basic, but my problem is that I feel lost at the same time. Like I'm memorizing all of this shit, but I wouldn't know what to apply them to when I make my game.
I tried reading "rpgs and math formulas" and I recognized the basic concepts that were taught, but I didn't know what the fuck was going on; I asked questions to myself like "why was this equation used?" as I read. https://www.redblobgames.com/articles/probability/damage-rolls.html

What should I do? Should I just keep taking notes and learn algebra?
Are there any sites out there that'll help a brainlet like me learn math and applying them into games I'll make?

There is another way to do this, but when I used integration by parts I get 0=1. What did I do wrong?

>>9575662
>Are there any sites out there that'll help a brainlet like me learn math and applying them into games I'll make?
I think your problem at the moment is that you aren't getting the intuition behind some of these concepts. You know how to plug in numbers but you're not understanding why it's done that way.

If you want to get the intuition, I highly recommend going through Khan Academy's catalogue, along with reading a stats textbook. If you need help with a specific problem, I might be able to help, so feel free to post anything that's tripping you up.
Good luck, dude!

I have two charged concentric spheres, small sphere with radius r and charge q and big sphere with radius R and charge Q.
How do I find the potential created by the the two spheres at a point that's at R> p > r?
I've tried V = kq/r + kQ/R but that doesn't give the right answer.
That formula works though if I'm finding the charge at the center of the spheres.

Consider a single real number, defined as the equivalence class of Cauchy sequences of rationals. What is the size of the set of equivalent sets?

Since a finite number of leading terms of any Cauchy sequence can do whatever they want it seems like at first glance it would be a countable set. But for any given sequence beginning with N terms we can change the order of these terms, and in my mind it is something like a powerset, meaning each real number is an uncountable set of Cauchy sequences.

Is this true?

>>9575705
you're evaluating that part outside of the integral wrong,

[math]1|_2^\infty = 1-1 = 0[/math]

try picking something else or doing a substitution like u=1/x maybe

>>9575567
>No, because you wouldn't see anything behind it, you retard.
How so? A Black Body is an object that absorbs radiations and doesn't radiated energy. It's the perfect camouflage.

>>9575991
It wouldn't be very sneaky to have a giant black blob appear on the road.

When is Kappa = 1 when solving the capacitance?
The problems in my book assume it's one, but I don't know how they got it when K is the ratio between with and without a dielectric.

How do I know if I’m stupid?

>>9570832
[math] \frac{2^{n}}{10^{\alpha}} = x [/math], x is the number with the part erased
so: [math] n = \frac{\alpha}{log_{10}2} + log_{2}x [/math]
i just need a way to estimate the [math] \alpha [/math] and i can do it

(i tried some numbers and for the ones tested, the n i got from the formula above would have a difference <0.1 when compared with the real number (don't know if bigger n would result in bigger deviations) )

>>9576075
>if the number is 1 I want 128
why not 16

>>9576082
>why not 16
because you need to erase at least half of it +1

ops, just saw it is wrong there

>>9576093
why not 1024

>>9576098
because it needs to be the lowest possible

/v/ can't solve this pls help :(

>>9576108
95

>>9576110
wrong

how do i type in latex code here?

>>9576111
you are wrong

>>9576134
>10*1+5 = 95

>>9576131
[math (delete this) ] code [/math]

>>9576145
>1^1 = 2

>>9576108
Insufficient information. A bottle is 10, a burger is 5, a pair of beer mugs is 2. The numerical value of a single beer mug cannot be inferred from the information given.

>>9576011
>It wouldn't be very sneaky to have a giant black blob appear on the road.
Who said anything about using it on Earth? It would making a perfect spacecraft cloaking device

If i am given a closed path line integral, can I use Greens theorem of circulation to evaluate the area, even if there in NOT a vector field? It is a simply connected region that is defined on the entire region.

>>9576212
>2/1

why am i good at chemistry but literal, actual retard-tier at maths?

>>9576494
>chemistry
rule of three

>>9576514
what?

>>9576514
Chemistry is the brainlet science field actual smart people will into physics

If you have an equation like a=b+c and then square both sides would you get a^2=b^2+c^2
or a^2=b^2+2bc+c^2.

>>9576623
the latter, which you can check by just substituting actual numbers

what is this symbol from? I swear I've seen it before in a /sci/ context but can't put my tongue on the name

>>9576663
https://en.wikipedia.org/wiki/Shoshinsha_mark

>>9576663
A book?

College is killing me, almost literally. It makes me feel so fucking alone and miserable.
Should i just quit?

>>9576855
>Should i just quit?
Yes.

If (x+1) = e^t than what will be x2 equal to?
I have come to conclusion that x2 will be equal to e^2t - 2e^t + 1
But the problem I am solving is fully correct except where I have to use that value

>>9577011
>I have come to conclusion that x2 will be equal to e^2t - 2e^t + 1
This is correct.

>>9574959
This stuff isnt really clicking for me.

But if I set the objective function to be the same as the constraint [math]x+y+2x[/math], then the set of optimal solutions should be on the triangle right? (with the maximum output being 1?)

As for the others I probably need to think some more. Not even sure if I'm thinking right

>>9577013
>>9577011
How?

x+1 = e^t
x = e^t -1
2(x) = 2(e^t-1)
2x = 2e^t - 2

>>9577112
>How?
I assumed x2 meant x^2.

>>9577100
> But if I set the objective function to be the same as the constraint [math]x+y+2x[/math], then the set of optimal solutions should be on the triangle right?
The objective function is a function, the constraint is an inequality. In the sense that they're both defined in terms of a vector, the vectors will be the same (up to a scale factor). But you have to get the sign right.

If you're maximising the objective function, then f=x+y+2z is valid for c). If you're minimising it, then f=-x-y-2z is valid. Note that f=-x, f=-y and f=-z are also valid solutions (for maximising the objective).

I tried but cant figure it out can any1 help?

>>9570387
Should I bother to do the "problem solving questions" that come at the end of each section in my textbook? I understand they're helpful but doing 110 questions per section is fucking tiring.

>>9577114
Yes I actually meant x^2

>>9577187
is that a or d there nigga

[math]Given \space obtuse \space \angle \space AOB, \space draw \space a \space ray \space OX \space so \space \angle \space XOB \space and \space \angle \space AOX \space both \space obtuse \space and \space equal \space to \space \angle \space AOB[/math]

Sorry what the fuck. Let's say AOB is 140grad, then 360-140 = 220 - I cant fit 2 obtuse equal angles in any way

Imagine a sea of composite integers remaining uninterrupted by prime numbers: maybe a thousand or a million or more consecutive composite integers. I haven't studied number theory, but I thought the idea was interesting.

How can I purposefully find a large group of composite integers? Is there a small subject based on large groups of composite integers?

Everyone seems to be looking for prime numbers, so I imagined a hidden sea of consecutive composites for fun.

>>9577226
>grad
a circle is 400 grad is it not?

>>9577281
what
you think of rad, not grad
Also, straight angle is 180 so it is 360 for both straight angles

>>9577283
https://en.wikipedia.org/wiki/Gradian

must be a language thing, if it is 360 we use "degrees"

Is somebody with a 140IQ twice as smart as somebody with a 70IQ?

>>9577287
not if IQ has a normal distribution

is pic related an ok definition for a colouring? also is there a difference between a colouring and a [math]\textit{proper}[/math] colouring
>>9575705
i think that [math] x=e^u [/math] is a better substitution. you should get [math] I=\lim\limits_{R\to\infty}\log^2R-\log^22 [/math]

Doesn't relativity theory prove geocentric model was true all along?

>>9577285
well yeah deg

Anyway I dont see how it is possible, how do you draw OX so all angles are obtuse and equal?

>>9577302

>>9577307
sorry hit reply too soon

it's only possible if I understand the question for a specific angle

>>9577300
You could describe the trajectories of all objects with Earth as your rest frame, but for certain purposes that becomes unnecessarily complicated. Describing the motion of Jupiter is easiest when you take the sun as your rest frame and describing the motion of the solar system through the milky way is easiest when you set the galactic center as your reference frame.
You could select the center of the Earth as your reference frame for everything and it'd be just as "valid" as describing the motion of a car driving down an Autobahn with the center of Andromeda as your reference frame, but why would you?
That said, this is only deciding where you choose the center to be for mathematical purposes. Heliocentrism is also neat because the motion of Mars is more affected by the Sun's presence than by Earth's. There are better physical motivations for choosing the Sun as your reference frame even though the maths will work out the same no matter where you put it (so long as you're not in a stupidly strong gravitational field or moving things close to the speed of light. On scales being talked about here, Galilean relativity works fine) .

>>9577307
>>9577309
you can clearly see they are not equal if AOB > 120deg

>>9577328
i agree it is only possible for exactly 120

Why is the carbonic-acid marked with this zero?

If its supposed to show zero charge, why dont i see this notation more often?

>i might have the terminology wrong
<sorry

Do I really need to go to my lectures? My school has them uploaded as well as all the notes online

>>9577438
I spent two of my three years in college doing this and I have never made a greater mistake in my life. Lecture notes are good (though they often don't contain all the necessary information explained in an easy to understand manner) I've been able to stay in my course by keeping on top of them and filling in gaps with textbooks, but it would have been way easier if I had attended lectures and I would be getting much better grades too.
Maybe you're more motivated and have more aptitude for absorbing written information than I did, but I still wouldn't recommend it. Assuming your lecturers are even semi-competent their explanations and descriptions that come from their understanding of a topic will give you more perspectives which will make it easier to grasp a topic. Also, being able to ask questions of an actual human being who can try and understand what you're not understanding is incredibly useful.

>>9571499
only if they filter mong in elementary

>>9571499
Nah, but they're the one of the first big filters that target mong who don't have diagnosable disabilities.

>>9572523
This. >>9572527
Your biological programming has given you desires and the culture you live in has given you numerous means to satisfy those desires.
Have sex, do what makes you happy, live a fulfilled life, etc.
You won't live to see the heat death of the universe. It should only be relevant to you because it's a cool idea that can either add or subtract value from your life depending on whether or not you enjoy learning about shit like that.
Your own death is only relevant insofar as you'd like to avoid it because that leaves you more time to have sex, solve problems, listen to Beethoven, etc.

https://www.youtube.com/watch?v=d-diB65scQU&ab_channel=BobbyMcFerrinVEVO

>>9570387
a) what would happened if we bombarded electron with photons?
b) can we bombard electron with photons?

>>9577367
can anyone help me with this?

>>9570387
guys, how can I prove by induction that
[math]\sum_{i\geq1}\lfloor\frac{N}{p^i}\rfloor = V_p(N!)[/math] where [math]p[/math] is a given prime (Legendre's formula) and [math]V_p(n)[/math] is the p-adic valuation of n?

I see why this is true, and I can think of a clear (though non-rigorous) proof, but the book I'm studying with claims that the simplest proof of this is through an induction on [math]N[/math]...

For the function x^2, f(x) = x^2 the derivative = 2x, which means its slope is 2x. The formula for slope is change in y / change in x, so for the earlier function if x = 2 then the slope would be 4. Thus using the equation of slope 4 = change in y / 2 and to find change in y it would be 4*2 = change in y which comes out to 8 but on a graph this isnt the case. Where am I wrong at?

so i'm 30 and going to college. i graduated highschool a bit early, about 14 years ago. i'm studying engineering, i have 4 classes and a lab, and i'm working hard to keep up with the course material. it's midterms and my current GPA is 3.92 and i still feel like i can do better. my point is, college is fucking easy, and yet about 2/3rds of each class has dropped out, and many of the remaining students are struggling. are there any other oldfags that can lend me some perspective? i don't remember highschool being this easy. i was taking AP classes during my senior year and it was hard as fuck. my current classes are a complete joke compared to highschool. has the curriculum been made easier since i graduated, or am i just an exceptional student?

Got a question here, thats kindo tough for me to answer:

Show that the medians of a triangle will, always, intersect in a given point, and that the heights of a triangle will intersect in a given point.

Anyone?

>>9578185
With height it is easy, you can use the theorem about perpendicular lines - a line perpendicular to another intersect only once and in one given point.

Therefore, you can draw only one perpendicular line from one vertex towards opposite edge.

Now sure about medians.

retardo here, I have a problem asking how much current would flow through a human who has grabbed a 13kV (1600ohm internal resistance) powersupply, and the human has 12 kilo ohms resistance along the path between his hands (cause he grabbed the powersource with both hands)
I boiled it down to this
Vab + IR = 0 (using the loop rule)
Vab = E - Ir = terminal voltage of power source
if we solve for I, then I = E / (r - R)
and when we plug in E = 13kV, and r = 1600 ohm (converted to kilo of course), and R = 12 kilo ohm, then I get 1.25 amperes
but apparently that's wrong
what the fuck do I do?

>>9578381
You should be adding the resistances, not subtracting them.

sup Anons,

not sure where to ask this or if or if not a request thread would be allowed so,

what if any educational/learning podcasts on /sci/ related topics might you recommend?

Bonus points if they can explain gauge symmetry to a brainlet like me.

>>9578381
>Vab + IR = 0
one of these terms needs to be negative (generally the voltage source) to apply KVL

How strong is the electric field inside the plates of a capacitor whose plates are 2.0-mm apart and
charged to 92 microC each? (There is no dielectric between the plates.)
E= V/D
V = CQ
How the fuck do i solve this when I'm only given 2 pieces of information?
C requires area, and I don't have that.

>>9578185
Show for equilateral triangle, then argue that any triangle is the image under an affine (linear) map of an equilateral triangle, and all the crap is preserved.

>>9578084
Derivative is slope of the tangent line, not slope of line through the origin

>>9577708
Assuming the electron is bound to an atom:
Depending on the energy of the photon:
1) Nothing because the photon is too low an energy.

2) The electron would absorb the photon and become excited. It could then re-emit the photon. That's what fluorescence is.

3) the electron would gain enough energy to leave the atom. This is what ionization is and it's why high energy radiation like xrays are so harmful. It can rip the electrons off the atoms in your D&A which can result in copying errors when your cells divide. This usually manifests as cancer.

If the electron isn't bound to an atom as in a plasma, you'd just be imparting momentum to the electron which it can also re-emit as a photon if the conditions are right.


It's also maybe worth nothing that photons happens to be the way that electrons and other charged particles interact as in the Feynman diagram in pic related. The electron on the left emits a photon which changes it's momentum and the one on the right absorbs the photon which changes it's momentum . The two are essentially "bombarding" each other with photons in the act of repelling each other. There's a lot of electrons and protons doing this and so the space around you is effectively a seething sea of photons as every charged particle communicates it's existence to every other charged particle in the observable universe.

How to I find derivative of higher order multivariate functions?

I don't get this part
why does [math]\frac{\partial}{\partial t}\frac{\partial z}{\partial x}=\frac{\partial ^2z}{\partial x^2}\frac{\partial x}{\partial t}+\frac{\partial ^2z}{\partial x\partial y}\frac{\partial y}{\partial t}[/math]

I really don't get why the chain rule was used here

>>9579119
*product rule

>>9578996
just do it a bunch of times

>>9578447
>>9578515
Thanks for catching that clerical error!

>>9578717
E is a is a function of distance between charges.
Q = CV
E = V/d

E = (Q/C)/d

yeah wtf you need C