/sqt/ Stupid Questions Thread

[Anonymous No.9527179]

This thread is for questions that don't deserve their own thread.

Tips!
>give context
>describe your thought process if you're stuck
>try wolframalpha.com and stackexchange.com
>How To Ask Questions The Smart Way http://www.catb.org/~esr/faqs/smart-questions.html

Previous thread >>9516225

[Anonymous No.9527189]

Why is there something instead of nothing?
If God is benevolent, why does he allow the existence of hell?
How do neurons give birth to consciousness?
If the universe is moving towards chaos, why does life seem so well organized?
What is beyond the external wall of the universe?

[Anonymous No.9527192]

why is life so frustrating?

[Anonymous No.9527220]

will becoming good at math help me find a girlfriend

[Anonymous No.9527233]

>>9527220
yes

[Anonymous No.9527427]

>>9527189
This isn't a philosophy board

[Anonymous No.9527583]

Can anyone give me an idea for part (c)? I did (a) and (b) but dont know where to start for pipelining it. I got iteration bound as 18 ns and critical path delay as 88 ns.

[Anonymous No.9527621]

>>9527189
>Why is there something instead of nothing?
God wills it.
>If God is benevolent, why does he allow the existence of hell?
If your parents love you, why don't they do everything you want?
>How do neurons give birth to consciousness?
God hacked it in.
>If the universe is moving towards chaos, why does life seem so well organized?
Energy was spent on it.
>What is beyond the external wall of the universe?
Manifolds need not be embedded in anything.

[Anonymous No.9527624]

>>9527220
Only if you get rich and only until they divorce you taking everything with them.

[Anonymous No.9527627]

>>9527192
The point is to deal with it.

[Anonymous No.9528071]

>>9527179
I'm writing a research project on quantum vs classical computers. I know almost nothing about theoretical cs, and absolutely nothing about quantum mechanics. I need to compare turing and quantum turing machinea in terms of what is computable by them. And i already know that their boundaries are the same. What i need are legit academic sources. Or i need to conclude that myself based on their definitions. It would be really if someone could post the link here, but i'm not hoping on that. So how can i conclude that from their definition? I can't even understand how quantum tm is defined. What parts of their design say that they can compute same things?

[Anonymous No.9528234]

>>9527621
>Manifolds need not be embedded in anything.
Every manifold is trivially embedded in itself.

[Anonymous No.9528285]

We cannot say that [math]i = \sqrt{-1}[/math] because [math]i[/math] doesn't observe the property of square roots such as [math]\sqrt{a}\cdot \sqrt{b} = \sqrt{a\cdot b}[/math]. We can say that [math]i[/math] is the number which satisfies [math]x^2 + 1 = 0[/math] but there are two such numbers.

Both of these points are usually ignored in high school. Why are high school teachers so terrible?

[Anonymous No.9528292]

>>9528285
>Why are high school teachers so terrible?
Because you went to a high school for brainlets.

[Anonymous No.9528312]

What's the point of maths? Specifically, what is the point of some proofs theorems or problems? For example, recent video, what's the point of the catalan's conjecture? Or illumination problem? They have no real life applications, other than to simply prove a point.

[Anonymous No.9528314]

>>9528285
Never seen a teacher write [math]\mathrm i\,=\,\sqrt{-1}[/math].

[Anonymous No.9528317]

>>9528285
>We can say that i is the number which satisfies x^2+1=0
We can't. This is unrigorous garbage.

[Anonymous No.9528322]

>>9528317
>This is unrigorous garbage.
don't hurt yourself kid

[Anonymous No.9528323]

>>9528322
Excuse me?

[Anonymous No.9528324]

>>9528317
>We can't.
Speak for yourself.

[Anonymous No.9528327]

>>9528323
You're excused kiddo

[Anonymous No.9528328]

>>9528312
Post your face when you realize that "real life applications" are also just proving a point.

[Anonymous No.9528337]

>>9528285
Complex numbers are literally just fiction. They don't exist.

[Anonymous No.9528339]

>>9528337
so are integers

so is zero

[Anonymous No.9528340]

>>9528337
>Complex numbers are literally just fiction. They don't exist.
All mathematical objects exist.

[Anonymous No.9528355]

>>9528328
Yes, and no. At least real life applications are actually useful, I see no use in knowing catalan's conjecture. It's fun to know, sure, but other than that...

[Anonymous No.9528356]

>>9528339
You can prove the existence of integers, not so with the complex "numbers".
>>9528340
They exist in the same sense fiction exists, as in they exist on some physical medium used to record them.

[Anonymous No.9528360]

>>9528356
>You can prove the existence of integers
No you cannot.

[Anonymous No.9528363]

>>9528355
>At least real life applications are actually useful, I see no use in knowing catalan's conjecture.
The transition from mathematics to applications can take centuries, just look at how long prime numbers took to be used for cryptography.

[Anonymous No.9528365]

>>9528360
You can, since free groups can easily be shown to exist.

[Anonymous No.9528367]

>>9528365
>free groups can easily be shown to exist.
No they can not.

[Anonymous No.9528373]

>>9528367
Yes they can.

[Anonymous No.9528383]

>>9528355
>actually useful
This is a meaningless thing to say without further elaboration.

[Anonymous No.9528387]

>>9528356
>You can prove the existence of integers
yeah, nah

God gave us 1. That's it. Everything else is made up bullshit.

[Anonymous No.9528400]

>>9528383
Okay, explain to me the use of the catalan conjecture, how would you apply it to real life problems?

>>9528363
I see your point.

[Anonymous No.9528401]

>>9528387
>God gave us 1.
Which is all you need to show the existence of integers since they are finitely generated by 1.

[Anonymous No.9528407]

>>9528400
>explain to me the use of the catalan conjecture
I couldn't care less about it, I'm not a n*mber theorist.
>how would you apply it to real life problems?
Why should I be applying it to "real life problems"? And what do you mean by "real life problems"?

[Anonymous No.9528420]

>>9528401
>finitely generated
This is a meaningless notion.

[Anonymous No.9528426]

>>9528420
>This is a meaningless notion.
This is a meaningless notion.

[Anonymous No.9528445]

>>9528407
Real life problems as in, does it serve to further any current mathematical problem or does it help solve, for example, how tall a building should be? From my point of view, seems like some of these are just proof for the sake of proof, same as if you get a fake plant for your house, it serves no purpose.
If you don't even care about it, why reply in the first place?

[Anonymous No.9528481]

what does this question actually want?

[Anonymous No.9528518]

>>9528445
>does it serve to further any current mathematical problem
That kind of n*mber theory isn't really mathematics, so no. It might have mathematical value if the proof involves developing new mathematics or using known techniques in innovative ways, which is usually the case with longstanding conjectures.
>does it help solve, for example, how tall a building should be?
This is as retarded as asking if some new research in biology helps calculate how long a certain bridge should be. That's simply not something biologists have as a goal.
>seems like some of these are just proof for the sake of proof
Some people seem to be interested in showing it to be true and a proof is the only way of doing so.

[Anonymous No.9528540]

>>9528481
It wants you to calculate the angle KJL to one decimal place.

[Anonymous No.9528565]

>>9528540
I dont understand what that means
I got angle X to be 48.2 deg

[Anonymous No.9528618]

>>9528565
So then you calculated angle KJL to one decimal place. What is there to understand?

[Anonymous No.9528632]

>>9528618
I just dont understand the question

[Anonymous No.9528643]

Which vitamins against dry skin?

http://www.strawpoll.me/15106676

[Anonymous No.9528644]

>>9528632
So you just accidentally did it correctly, is that it?/

[Anonymous No.9528654]

>>9528644
I dont get what "angle KJL" means. I worked out angle X.

[Anonymous No.9528659]

>>9528654
Perhaps you can deduce what it means from the conversation we're having.

[Anonymous No.9528663]

>>9528659
I get it but it is terrible wording.

[Anonymous No.9528677]

>>9528663
the wording is fine, you've just never seen an angle written like that before, it's pretty common way though

[Anonymous No.9528680]

>>9528663
What if the label "x" wasn't there?

[Anonymous No.9528703]

>>9528680
Oh yeah that makes sense
>>9528677
So basically work out all angles?

[Anonymous No.9528727]

My professor wants this information for a lab. It says in one box, I need: "Hydrogeologic Unit, Lithology, characteristics, depth and thickness." What the hell is a Hydrogeologic Unit? What am I suppose to be writing in? Under the information it describes the 4 aquifers and what they're made of. I don't know what to put there. My professor never answers emails.

[Anonymous No.9528731]

>>9528727
FOUR SCOOPS

[Anonymous No.9528736]

>>9528731
sexeh~

[Anonymous No.9528746]

>>9527179
Can someone explain where the differential come in? I have no idea how hey just sort of happen like bam they are there and all.

[Anonymous No.9528754]

>>9528746
It seems they are "considering the interval" and "considering the change in momentum." This is the likely source.

[Anonymous No.9528790]

>>9528736
>>9528731
No, really, I have no idea what my professor wants.

[Anonymous No.9528816]

Do I go to a brainlet university?

[Anonymous No.9528820]

Does DNA Polymerase only work with DNA or can it work with RNA too?

They asked me that in an interview, and I said just DNA.

Am I wrong?

[Anonymous No.9528824]

>>9528816
>Do I go to a brainlet university?
If you have to ask, yes.

[Anonymous No.9528827]

>>9528816
>prove prove prove prove prove
depends on your major

proofs are important to some endeavors

[Anonymous No.9528848]

>>9528820
I know RNA polymerase works with DNA and RNA, but DNA Polymerase only works with DNA right?

RIGHT?

my getting the job depends on this guys

[Anonymous No.9528858]

>>9528816
>considering modules over fields for no good reason
Absolutely. Losing this much generality is only something true brainlets would do.

[Anonymous No.9528860]

>>9528858
>>considering modules over fields for no good reason
Who are you quoting?

[Anonymous No.9528864]

[math]/iff{a}{b}
Breast

[Anonymous No.9528868]

>>9528860
This is a meaningless notion.

[Anonymous No.9528878]

>>9528864
[math]/iff{a}{b}[/math]

[Anonymous No.9528884]

>>9528878
[Math] a {/iff} b [/math]

[Anonymous No.9528887]

>>9528884
use the previewer you fucking retard

[Anonymous No.9528888]

>>9528884
[math] a {/iff} b [/math]

[Anonymous No.9529034]

>>9528703
>So basically work out all angles?
[math] \angle KJL [/math] is only one angle, specifically it is the clockwise angle from the ray JK to the ray JL where J is the vertex.

It's incredibly useful notation when dealing with lots of angles that share a vertex as well as it allows you to write a question without the need for a picture

[Anonymous No.9529131]

I need to do finite element analysis of a furnace, i want to see how hot the inside and outside will get. I have the model and materials, but i cant figure out the boundary conditions.
I know the amount of power put in the furnace, but i cant find any boundary condition for power.
For the wall i cant set a constant temperature since thats what i want to get, do i create a small portion of air surrounding the outside and set the air to constant temperature?

[Anonymous No.9529310]

Whats the general solution to this differential equations? I got Ce^t/1+Ce^t . However all online calculators are giving different answers

[Anonymous No.9529385]

Do quantum fields like the weak force field pervade the whole Universe all the time, or are they created serperate from each other like electromagnetic fields?

[Anonymous No.9529390]

>>9529310
https://en.wikipedia.org/wiki/Logistic_function

[Anonymous No.9529678]

>>9527179
Is the brainlet meme meant to be ironically stupid? I would think factors such as neuron density, neuron connections, brain structure, and brain to body mass ratio have much more to do with intelligence than brain size.

[Anonymous No.9529681]

>>9527189
Life is only 'organized' through our own limited human perception. It's just a coincidence, just one possibility out of infinitely many of them.

>>9527192
You're the one deciding to make it frustrating.

>>9528285
The unary operation "square root" is defined to be IR x IR -> IR. Extending it for complex numbers makes most of the properties unusable (as the one you pointed out), as an operation or a function. It's silly to extend it. Just as the logarithm.

>>9528312
It doesn't. Nothing 'has' a point, really. Anything in math could be useful in any or other way, it's just a matter of perspective

[Anonymous No.9529720]

>>9527179
That pic always reminds me of these.

[Anonymous No.9529848]

If I learn calculus from Spivak, can I do computations like the shit from stewart as well?

[Anonymous No.9529864]

>3rd world shithole uni
>fluid mechanics in this semester
>not even finished statics, dynamics, strength and thermo
>not even finished calc 3

How fucked I am and what can I do?

[Anonymous No.9529920]

Should linearizing data in different ways produce different lines of best fit? On variable is the square root of the other, and the slope for the line of best fit differs from the other by about 20% depending on whether I square one variable or take the square root of the other.

[Anonymous No.9530030]

>>9529864
How are you in fluid mechanics? You seem to lack prerequisite knowledge.

[Anonymous No.9530031]

Is everyone a fucking retard except me? I spent months terrified of taking the GRE because all the resources online seem to be measured towards room-temp IQ Indian kids, then I take the damn thing, and I scored near perfect. Anyone else have similar experiences?

[Anonymous No.9530043]

>>9530031
I’ve had a similar experience on every standardized test I’ve ever taken.

[Anonymous No.9530053]

>>9530031
>Is everyone a fucking retard except me?
Do you need to swear?

[Anonymous No.9530055]

>>9530043
Seriously I got a perfect SAT and didn't prep at all.

>tfw don't know what I want to do with my life so I'm sending my near perfect GRE to dozens of schools and programs hoping one of them is neat, but i know I'll end up just picking one at random like I did for undergrad

>>9530053
No, sorry.

[Anonymous No.9530165]

Could someone help me with 4.10.12?

I've been trying to figure it out first a couple of hours. The book doesn't really have a good example to follow and I'm too brainlet to figure it out. I think you're supposed to represent the integrand in terms of u ,w , and v, but I can't get them to work back out to the original. Could someone point me in the right direction?

[No Hwk No.9530166]

>>9530165
No. This board is not a homework help board.

[Anonymous No.9530194]

>>9530166
why not

[Anonymous No.9530206]

>>9529310
but that solution is wrong

[Anonymous No.9530256]

>>9530165
It's a fucking sphere of radius 2 dumbass, are you blind?

∭r^3 r^2 sin(θ)dϕdθdr = 4π ∫r^5 dr =4π/6 2^6 = 2^7 π/3

[Anonymous No.9530260]

>>9530165
It's a fucking quarter sphere of radius 2 dumbass, are you blind?

1/4 ∭r^3 r^2 sin(θ)dϕdθdr = π ∫r^5 dr =π/6 2^6 = 2^5 π/3

[Anonymous No.9530271]

>>9530256
I understand that it's a sphere of radius 2 and I know how to use the spherical coordinates, but I'm not sure how to do the intermediate step, I tried to convert directly to spherical coordinates but I couldn't get it to work and I can't figure out the part about the slice of melon, I think I need some algebra trick but I'm not sure what it is.

[Anonymous No.9530279]

>>9530165
What book is that?

[Anonymous No.9530285]

>>9530279
Hubbard and Hubbard: Vector Calculus, Linear Algebra, and Differential Forms

[Anonymous No.9530314]

>>9530271
It's a lemon slice since z>=0 and y>=0 (think northern hemisphere cut in half). But it's the integral of |r|^3 is so you can double both ranges and add a factor of 1/4.

Or you can just do 0<θ<π/2 and 0<ϕ<π. Either way, it's trivial as fuck.

[Anonymous No.9530384]

I see now, my professor told us to "Read the note in the margin!" and I thought it was implying that we had to parameterize it. That's what messed me up

[Anonymous No.9530445]

If space is expanding does it mean that everything (and everyone) is in theory bigger each second? Is there any way to relate the expansion to meters (or rather current meters if space is expanding)?
Is time expanding too?

[Anonymous No.9530492]

>>9530445
bigger compared to what? space? how would we know that space is getting bigger if matter grew at the exact same rate?

[Anonymous No.9530557]

What does the dot product of vectors actually represent, why am I calculating these numbers

[Anonymous No.9530624]

>>9529920
Yes, it should change the slope. Squaring both variables will change the distribution of sample points and give greater weight to smaller values.

[Anonymous No.9530626]

is there a word for "non set elements of set? like {{1,2},{3,4,5},{6,7}} the cardinality of this set is 3 but is there something I can use to refer to the amount of non-set elements? which in this case would be 7

[Anonymous No.9530644]

>>9530626
>is there a word for "non set elements of set?
No.

[Anonymous No.9530648]

>>9530626
>non-set elements
There is no such thing as long as you're working in usual set theory.
>which in this case would be 7
That would be the cardinality of the disjoint union of every set in your set {{1,2},{3,4,5},{6,7}}.

[Anonymous No.9530653]

>>9530648
>That would be the cardinality of the disjoint union of every set in your set {{1,2},{3,4,5},{6,7}}
yeah but that wouldn't be such a simple answer if it was like {{1,2},{3,{4,{5,6}}},{7,8}}.
i just want a word that describes how many non set elements are within a set down to any amount of subset layers. {{1,2},{3,{4,{5,6}}},{7,8}} would be 8.

[Anonymous No.9530655]

>>9530653
>i just want a word that describes how many non set elements are within a set
The word you're looking for is "zero". Every element of a set is itself a set.

[Anonymous No.9530661]

>>9530655
okay then say im not even talking about strictly set theory anymore
i just want a word for this concept

[Anonymous No.9530678]

>>9530661
I think you would say members of a set, the amount of which is the cardinality.

[Anonymous No.9530701]

>>9530206
No shit. That's why I'm asking the question

[Anonymous No.9530711]

>>9530661
The simplest answer was already given to you.

[Anonymous No.9530724]

Going to have to learn a fuckton of anatomy on the fly purely from lecture slides. Best way to do it? Currently use Anki but it feels like a lot of the image based stuff won't stick, plus items inside a cadaver can look WAY different.

[Anonymous No.9530745]

Should I focus my Engineering studies on something like space technology to get away from the decaying Earth, or should I try to focus on something to try and help turn this shithole back on the right track?

[Anonymous No.9530751]

Can someone explain to me how the FUCK you read IR and NMR spectroscopy. Like how you use NMR to determine structure? gen chem 2 exam in 12 hours

[Anonymous No.9530770]

is it a good idea to major in math if i'm stubid?

[Anonymous No.9530796]

So /sqt/ I'm too retarded to come up with a solution for this linear algebra problem.
Let [math]r, s[/math] be two straight lines living in the [math]\mathbb{R}^3[/math] space, given in cartesian or parametric form doesn't matter.
Find the equations for the plane [math]\pi[/math] that contains [math]\r[/math] and it's parallel to [math]s[/math].

I can understand how this would work if the lines are already parallel but if the two are crooked how can I?

[Anonymous No.9530801]

>>9530770
No join me in ee

Any idiot can do ee

[Anonymous No.9530804]

>>9530801
thanks

[Anonymous No.9530816]

>>9528367
do it right now

[Anonymous No.9530819]

>>9528387
how many 1's did God give us?

[Anonymous No.9530835]

[eqn]
\sqrt{i} \cdot \sqrt{i} = \left( \sqrt{i} \right)^2 = i \\ \\
\sqrt{i \cdot i} = \sqrt{\sqrt{-1} \cdot \sqrt{-1}} = \sqrt{ \left( \sqrt{-1} \right)^2} = \sqrt{-1} = i
[/eqn]

u wot m8

[Anonymous No.9530840]

>>9530835
was for
>>9528285

>>9530796
Find a point [math]P[/math] that lies on [math]r[/math].
Find vectors pointing in the directions of [math]r[/math] and [math]s[/math], respectively.
Example:

[eqn]
\vec{r} = \vec{r_p} + a \cdot \vec{r_d} \\ \\
\vec{s} = \vec{s_p} + b \cdot \vec{s_d} \\ \\
\vec{\pi} = \vec{r_p} + c \cdot \vec{r_d} + d \cdot \vec{s_d}
[/eqn]

[Anonymous No.9530857]

>>9528285
There's a perfectly fine field automorphism [math]\phi:\mathbb{C}\to\mathbb{C}[/math] that sends [math]\mathbb{R}\mapsto\mathbb{R}[/math] and [math]i\mapsto i[/math].

In fact, in general there's no "the" square root for a number, there's "a" canonical square root.

[Anonymous No.9530872]

>>9527179
What are some real-world uses for the derivative?

[Anonymous No.9530874]

>>9530872
FM radio

[Anonymous No.9530879]

>>9528071
Bro I dont know wtf you are talking about but here you are few sources from knowledgeable people in the field.

>https://media.ccc.de/v/22C3-1077-en-quantum_entanglement
>https://media.ccc.de/v/31c3_-_6157_-_en_-_saal_6_-_201412301245_-_diamonds_are_a_quantum_computer_s_best_friend_-_nicolas_wohrl
>https://media.ccc.de/v/31c3_-_6261_-_en_-_saal_2_-_201412291245_-_let_s_build_a_quantum_computer_-_andreas_dewes
>https://media.ccc.de/v/30C3_-_5536_-_en_-_saal_g_-_201312271830_-_long_distance_quantum_communication_-_c_b

[Anonymous No.9530885]

>>9530724
Download anatomy atlas from Netter.
Get some good anatomy textbooks online.
Sit down and study the human body in detail.
It help if you have some paper if front of you to sketch things out.
When you get to cranial nerves ect. I suggest you look for lectures on youtube.
There is one Indian guy with very bad accent that really knows his stuff and actually helped me a lot to visualize what is where.

[Anonymous No.9530970]

How would I solve for the dimensions of the top and bottom widths, marked in red? Is it even possible with the information given?

[Anonymous No.9530974]

does zero, the number, have any energy or weight? i mean, the fact that we can represent it, already gives it a name, an energy and existence. then, if i multiply infinite zeroes, will they start to create some mass? too brainy for you?

[Anonymous No.9530981]

>>9530974
numbers don't exist

[Anonymous No.9530990]

>>9530970
>Is it even possible with the information given?
no

[Anonymous No.9531103]

>>9527189
>Why is there something instead of nothing?
Logos.
>If God is benevolent, why does he allow the existence of hell?
Basically hell is nonexistence, or continued existence by other means, without life, in the form of unconscious matter perhaps, your 'being' taken to pieces and scattered, unable to come together for eternity. This is analogous to hellfire. If you were never a human being it would be different, but because you are a conscious person you have accumulated a soul, which can either manacle itself to the inanimate or build itself up immaterially in God by acting in accordance with its beatitude. The reason this -must- happen is because it is necessary for the consummation and instrumentality of things for there to be such a thing as non-existence in contrast with existence, since reality itself is bracketed by these two opposites and could not exist otherwise.
>How do neurons give birth to consciousness?
This is a mystery for the most part, all I can do is speculate but my attitude towards it is that consciousness is cumulative with the complexity of a given system, but mere complexity isn't enough, it must have organization too. Complexity without organization is noise, organization without complexity is inanimate, you need both, and it seems to me that the extent to which these qualities are combined in a given system is dependent upon the ends to which its operations are oriented, which of course depends on the causes that have produced said operations.
>If the universe is moving towards chaos, why does life seem so well organized?
Because the universe still quite young
>What is beyond the external wall of the universe?
There is no wall, the wall moves with the last particle, if you were to go past it you would only push it further. To actually go past it you need to be immaterial, so it is probably heaven, God or w/e.

[Anonymous No.9531106]

>>9530874
How would it be applied though?

[Anonymous No.9531122]

>>9530872
Spline interpolation. Autotuning. Spectroscopy.

[Anonymous No.9531130]

>>9531122
So basically fancy approximation?

[Anonymous No.9531134]

>>9531130
that's literally how limits are defined so yes

[Anonymous No.9531148]

>>9530835
Try it with the square root of (-1 times -1)

[Anonymous No.9531170]

>>9528848
You lost the job my friend

[Anonymous No.9531177]

>>9531170
>>9528848
Just kidding, you answered correctly

[Anonymous No.9531286]

how the hell can computer and mobile screens reproduce grey?
grey light is impossible r-right?

[Anonymous No.9531322]

>>9531286
pink is also impossible

[Anonymous No.9531495]

Sup guys, Physics major here and I was wondering how likely I would be able to land a job in the semi-conductor/superconductor industry without an internship?
I will most likely have to attend a summer session for a required class that can't be taken during the regular school year because of how full it gets and because I also have to get into my physics class. Is there any hope of employment without an internship?

[Anonymous No.9531511]

A sequence [math]a_n[/math] converges to a real number [math]L[/math] iff for every [math]\epsilon>0[/math] there exists a number [math]N[/math] such that [math]|a_n - L|<\epsilon[/math] for all [math]n\geq N[/math].

How to go about finding N? [math]|a_n - L | = [/math] something less than epsilon, so you can get a relationship between n and epsilon. Then what?

My book doesn't use the delta epsilon convention so it's difficult to google examples in the form written.

[Anonymous No.9531539]

>>9531511
consider the sequence [math]s_n = \frac{n}{n+1}[/math] and we suppose that this sequence converges to [math]1[/math]. Then we can demonstrate this if for every epsilon etc.

So someone gives us an epsilon, and we want to show that [math]L - s_n < \epsilon[/math]. Well [math]1 - s_n = 1 - \frac{n}{n+1} = \frac{1}{n+1}< \epsilon[/math] which I am sure you can use to determine a criteria on [math]N[/math].

[Anonymous No.9531572]

>>9531539
So if [math]N=\frac 1 \epsilon[/math], then
[math]1 - s_n = \frac {1}{n+1} < \frac{1}{n} < \frac 1 \epsilon < \epsilon [/math] ?

[Anonymous No.9531590]

[Boolean algebra question]

Why is the result of using the distributive property here not F_3 = A‘B‘CD + ABC‘D‘ + 1 + 1? Because AB * A‘B‘ should equal 1 should it not? Likewise with CD * C‘D‘ .

Where do they put the two ones?

[Anonymous No.9531592]

>>9531572
You can explicitly resolve the inequality by expressing [math]n[/math] in terms of [math]\epsilon[/math] in which case you have [math]\frac{1}{\epsilon}-1 < n[/math].

[Anonymous No.9531605]

>>9531590
AB*A'B' = 0 bro

[Anonymous No.9531629]

>>9531605
Oh I see I was looking at the addition postulate not the multiplication postulate thank you

[Anonymous No.9531721]

can someone help me understand implicit differentiation?

[Anonymous No.9531739]

>>9530816
>do it right now
Do what?

[Anonymous No.9531743]

>>9531721
probably someone can, if you explain how you could possibly fail to understand it

it's literally the chain rule

[Anonymous No.9531762]

>>9531743
I get that, just having trouble understanding why it works

[Anonymous No.9531774]

why is log base 10 generally the most common?

[Anonymous No.9531777]

>>9531774
it's not.

[Anonymous No.9531785]

>>9531762
Do the same thing to both sides until the derivative shows up isolated on one of them. Take derivatives of both sides by remembering to use the chain rule. That's all there is to the concept.

[Anonymous No.9531787]

>>9531777
it's the default for most calculators though

[Anonymous No.9531801]

>>9531787
Any decent calculator will have an LN button. Taking a logarithm basically always means natural log.

[Anonymous No.9531812]

>>9531592
Sorry to be dumb but...

So you establish the relationship between n and epsilon, from that you can choose your N. How do you compose your proof using the precise definition?

You would just say let N equal the inequality you found less than N relating to epsilon? So,
[math]|a_n - L| < \epsilon[/math] when [math] N = \frac {1}{\epsilon} - 1[/math] is sufficient?

[Anonymous No.9531821]

>>9531812
N needs to be natural

[Anonymous No.9531847]

>>9531590
[math]
E := (AB + CD) \\
\begin{align}
F_3 &= E(A'B'+C'D')\\
&= (A'B'E) + (C'D'E)\\
&= A'B'(AB+CD) + C'D'(AB+CD)\\
&= A'B'AB + A'B'CD + ABC'D' + CDC'D'\\
&= 0 + A'B'CD + ABC'D' + 0\\
&= A'B'CD + ABC'D'\\
\end{align}
[/math]

[Anonymous No.9531898]

A stupid question but i hope someone can answer it.
You are watching a horse race with 10 participants numbered from 1 to 10. What are the chances of horse number 6 beating 4,5 and 9?

[Anonymous No.9531955]

>>9531774
Pulling it out of my ass, I would assume 10 exponentals are easier to work with or scientific notation.

[Anonymous No.9532008]

>>9531898
Zero since the house wins every time.

[Anonymous No.9532045]

>>9531511
You have to choose a candidate (what you think the limit is), then prove it using the relationship between e and x(n).

For example, for the sequence x(n) = 1/n we can prove that the limit L is 0:

Choose N = [1/e] + 1 , where [1/e] is the greatest natural number less than or equal to 1/e.

For all n > N, | x(n) - 0 | <= x(N) = 1/([1/e]+1) < e. Proof:

For any non-zero real number r, 1/((1/r)+1) = r/(r+1).

r/(r+1) < r for all non-zero real numbers, so 1/([1/e]+1) < e.

N = [1/e] + 1 gives x(N) = 1/([1/e]+1) in the sequence x(n) = 1/n.

To recap, we have proven that x(N) = 1/([1/e]+1) < e. Now we only need to prove that | x(n) - 0 | <= x(N) for all n > N.

| x(n) - 0 | = x(n) for all positive reals, so we need to show that 1/(n) <= 1/N for all n < N , for this I'll use a proof by induction.

Using n = N+1 as a base case, x(n) = 1/n = 1/(N+1) < 1/N.

n+1 = (N+1)+1 , x(n+1) = 1/((N+1)+1) < 1/(N+1) = 1/n , x(n+1) > x(n) for all n.

Because we have proved: for all n>N , | x(n) - 0 | <= x(N) = 1/([1/e]+1) < e. We have proven that the limit of the sequence x(n) = 0 by definition of limit, and x(n) = 1/n , the limit of the sequence 1/n is 0.

[Anonymous No.9532181]

Can any of you brainlets explain why I can't remember names? Is it a long term or a short term memory problem???

[Anonymous No.9532253]

If you flew a manned rocket into the sun what would you die of? Would you die from the heat or would something else kill you before that? Like radiation or some shit.

[Anonymous No.9532286]

>>9532253
How would anyone know that dipshit?

[Anonymous No.9532328]

>>9530711
was it "no"
why are you pissed at me anyway, you can always tell someone is angry when they use correct punctuation and capitalization and the fact that >>9530644 is a one word response adds insult to injury

[Anonymous No.9532374]

Anyone know a thing or two internal heat?

Internal energy change is the sum of heat and work. Explain why the internal energy change of the reaction between hydrochloric acid and sodium hydroxide can be determined with only a small error by determining the heat of the reaction.Explain why the error would be larger if sodium carbonate is used as the base in place of the sodium hydroxide.

Can help me?

[Anonymous No.9532551]

How do I set this integral for Electric Field in terms of r?
E = 1/4piEo * 1/(r^2)dq
Integral is 1/r^2 dq

[Anonymous No.9532554]

So what I have so far is:
B Transpose = 5x10
I = 10x5
The 0 in the top column is 10xn

I don't know what "BB transpose" means and if I'm supposed to assume every 0 matrix has the same dimensions.

[Anonymous No.9532614]

Taking a Discrete Mathematics class, we're discussing counting, permutations, combinations.

I'm given the string ABCDE, and the questions I'm on ask me how many substrings there are given certain restrictions. Specifically, I'm to find how many substrings there are that contain BC and DE.

My first thought is 'place the first substring, then the next, then the rest of the letters' BUT depending on where you place the first, you either have two or one place you can put the second. Am I on the right track here at least? Should I treat it like a case one and case two and add them together?

[Anonymous No.9532640]

How would you go about solving this? I'm this far in, idk how to proceed

This isn't a homework question, just a challenge question my teacher gave us in class that I couldn't solve

[Anonymous No.9532652]

How would you go about answering this? Not a homework question just curios

[Anonymous No.9532672]

>>9527179
Do I lose mass when I take shits?

[Anonymous No.9532743]

>>9532551
what is this shit, what type of charge do you have?

[Anonymous No.9532749]

>>9532743
There's no charge. I'm just supposed to rearrange the integral so that I can solve with respect to r.
Basically, changing the dq to dr from in the formula for an electric field.

[Anonymous No.9532762]

I need help with this, I just cant see any pattern.

[Anonymous No.9532786]

>>9532762
Prob the last one

[Anonymous No.9532808]

>>9532614
Same anon, way simpler than I was making it out to be. Treat LP, MN, and O as the elements to place first, then you're dealing with 3 spots to place LP, MN, or O. P(3,3) is the answer or just 6.

Getting there slowly but surely guys...

[Anonymous No.9532847]

>>9532786
You think so? I would like to hear your reasoning, since I still cant seem to understand

[Anonymous No.9532976]

>>9528727
It sounds like the hydrogeologic unit is an aquifer. And they want the lithology, depth, etc of those aquifers

[Anonymous No.9533081]

>>9527179
Is the perceived direction and rate of time merely a product of human physiology? If we're physical beings riding a wave of entropy through chemical and physical reactions then isn't our experience of time merely the result of our being pushed in the direction and rate which sustains our existence?

From an objective position is the universe an eternal cloud of potential energy?

[Anonymous No.9533097]

>>9531148
[eqn]
\sqrt{-1 \cdot -1} = \sqrt{i^2 \cdot i^2} = \sqrt{i^2} \cdot \sqrt{i^2} = \pm i \cdot \pm i = \pm 1 \\ \\
\sqrt{-1 \cdot -1} = \sqrt{1} = \pm 1
[/eqn]

Your point?

[Anonymous No.9533099]

We're being teached Prolog in my nonprocedural programming class. Should I take the language seriously, or is it just a CS meme?

[Anonymous No.9533101]

>>9533097
>multivalued "functions"

[Anonymous No.9533108]

>>9531286
Gray is any mixture of light that results in equal responses from all three color receptors in your eye, or, more simply, any mixture of colored light whose visible spectrum is flat. Monitors reproduce it by emitting equal* amounts of red**, blue** and green** light.

* Corrected for different frequency responses of each color receptor.
** Actually not exactly red, blue and green, but a reddish, blueish and greenish hue.

>>9533101
>every function must be bijective and injective
Oh you sweet innocent child.

[Anonymous No.9533111]

>>9533099
*taught
Maybe you should learn the English language before moving on to programming languages.

[Anonymous No.9533117]

>>9533111
Here, have a (You).

[Anonymous No.9533120]

>>9533108
>>every function must be bijective and injective
Who are you quoting?

[Anonymous No.9533121]

>>9533120
*whom
Your implied whining.

[Anonymous No.9533125]

2+2=?

[Anonymous No.9533131]

>>9533121
Where did he imply that? Are you genuinely retarded?

[Anonymous No.9533132]

>>9533131
>Where did he imply that?
I'm not a "he".

[Anonymous No.9533133]

>>9528746
The whole point is that you're comparing the value of momentum and velocity at time t and at a very slightly later time t + dt. At which point the momentum might be different by a tiny amount dm and the velocity might be different by a tiny amount dv. The differentials are just that, tiny differences in some variable from one point to the next. For calculus you just look at what happens as that time difference goes to 0 - a derivative is the limit of the ratio between two of these differentials, the value this ratio approaches as the interval goes to 0.

[Anonymous No.9533136]

>>9533131
My mistake, I keep forgetting that the injective property means that the INVERSE of a function is single-valued. It's been five years since I last had algebra. Carry on.

[Anonymous No.9533144]

>>9533136
>My mistake, I keep forgetting that the injective property means that the INVERSE of a function is single-valued. It's been five years since I last had algebra. Carry on.
What does algebra have to do with it?

[Anonymous No.9533146]

>>9533144
The most recent uni course in which this was talked about was called Algebra. Or was it a different course? In any case, it's been 5 or 6 years.

[Anonymous No.9533148]

>>9533136
>injective property means that the INVERSE of a function is single-valued
This makes no sense. The inverse of a function need not exist. Every function is single-valued, therefore every inverse of every function is also single-valued.

[Anonymous No.9533155]

>>9533148
>hahaha I am trolling this guy SO hard right now by using a uselessly specific definition of the word "function"

[Anonymous No.9533159]

>>9533155
>>hahaha I am trolling this guy SO hard right now by using a uselessly specific definition of the word "function"
Who are you quoting?

[Anonymous No.9533162]

>>9533155
>a uselessly specific definition of the word "function"
It is the definition used by every single mathematician. How is it "uselessly specific"? You seem to be retarded.
And fuck off to >>>/r/eddit/ if you want to use their images here.

[Anonymous No.9533165]

>>9533162
OK, then what do you call relations that are multi-valued?

[Anonymous No.9533172]

>>9533165
Such relations are uselessly specific and don't arise often in mathematics, so they don't have a special name. And I don't know the proper engineering term for them.

[Anonymous No.9533175]

>>9533172
>any even-numbered root
>inverse of any triangular function
>uselessly specific and don't arise often
We call them "functions". There is no need for a distinction between multi-valued functions and single-valued functions. Then again, I love sucking cock.

[Anonymous No.9533179]

>>9533175
>multi-valued functions
No such thing.

[Anonymous No.9533181]

>>9533175
>any even-numbered root
>inverse of any triangular function
These may arise in engineering, but certainly not in mathematics.
>There is no need for a distinction between multi-valued functions and single-valued functions.
One exists and the other is impossible by definition. So yes, there is no "need" for a distinction as the distinction is already obvious.
>reddit frog
Not surprised in the slightest. Subhuman redditors are known to have very low intelligence.

[Anonymous No.9533184]

>>9533179
You win this one.

[Anonymous No.9533200]

>>9533101
I would agree that "multi-valued function" is an abuse of notation.

>>9533108
Every function is injective by definition.

>>9533136
The inverse of a function is not always a function, consider: f(x) = x^2 .

If a function is surjective, and therefor bijective, there exists an inverse function.

>>9533165
It depends, generally they are just called relations.

>>9533175
There is a necessary distinction between single and multi-valued functions, they have many different properties.

>>9533181
If you're this caught up in notation you're going to have a lot of problems with the standard curriculum.

[Anonymous No.9533206]

>>9533200
>Every function is injective by definition.

[Anonymous No.9533207]

>>9533200
>The inverse of a function is not always a function

[Anonymous No.9533242]

The formula for the distance or the magnitude of a 3D vector is √(x*x+y*y+z*z). I have a vector for direction: (target vector - origin vector). After the magnitude formula is applied to the resultant vector, it gets the distance from
the origin to the target correct, while the formula never knew about the target's or the origin's vectors. How does this work? Is there any derivation for this formula or is it arbitrary?
Thanks

[Anonymous No.9533247]

>>9533200
>multi-valued functions
No such thing.

[Anonymous No.9533267]

I'm unable to integrate

(cos^2(x)-cos(x)+1)^(3/2)

could anyone give me some hints or may be show the solution?
I've tried symbolab/other int calcs, but it exceeds the computation time.

[Anonymous No.9533325]

Can someone provide me with proof in category theory that:
[math]id_A=id^{-1}_A[/math]

I think this might help me prove:
[math]id^-_A=id_{P(A)}[/math]

Where -1 is inverse and - is preimage.

[Anonymous No.9533341]

>>9533325
The first part is trivial from the definition of isomorphism.
>[math]id^-_A=id_{P(A)}[/math]
What are you trying to say? This would imply [math]P(A) = \bar{A}[/math], whatever they are.

[Anonymous No.9533348]

>>9533341
I probably have to do something along these lines though.

[math]id^-_A(A') = \{x|x \in A, f(x) \in A'\}[/math]
From definition of preimage.
[math]\{x|x \in A, id_A(x) \in A'\}[/math]
From definition of identity?

[Anonymous No.9533429]

>>9532045
Thank you. I don't know why my instructor couldn't have said this at least one time.

[Anonymous No.9533697]

How do I prove that if I have a square [math]ABCD[/math] with [math]P[/math] a point outside of the square such that the angle [math]<APB=\frac{\pi}{2}[/math] and we call [math]M[/math] and [math]M[/math] the intersections of[math]AB[/math] with [math]PD, PC[/math] respectively, then [math]MN^2=AM\times BN[/math]

[Anonymous No.9533846]

>>9533697
help plox

[Anonymous No.9533974]

>>9533341
I first now realized you must have misunderstood something.

If f: A --> B, then preimage f: P(B) --> P(A).

[Anonymous No.9534070]

Calc 2 question

With double and triple integrals, what exactly is the point of distk guishing between "type 1," "type 2," and "type 3" regions? Theres all this nonsense about how you start with the dx and make it a function of y etc etc but it all seems kind of meaningless to me. You have a geometric region and you integrate with respect to some orthonormal basis of this region, eliminating one parameter for every integral. Right?

[Anonymous No.9534087]

Boolean Algebra

If I had he expression F = ABC + AB'C' ,
would it be legal to say that F = A(B + B')(C + C')
and thus F = A ?

[Anonymous No.9534091]

>>9532762
can anyone give the pattern?

[Anonymous No.9534094]

>>9534087
the*

[Anonymous No.9534106]

>>9534087
If that factorization were correct, then yes. But that factorization is not correct which you can see if you multiply it out.
(B+B')(C+C') = BC + B'C' + B'C + BC'
and there's no reason to eliminate the B'C or BC' terms

You can consider this sequence with a double negation introduction to turn AND into OR
ABC+AB'C'
A(BC+B'C')
A(BC+(B'C')'')
A(BC+B''+C'')
A(BC+B+C)
A(B(C+1) + C)
A(B+C)
AB+AC

[Anonymous No.9534122]

>>9534087
Suppose A=1, B=1, and C=0

Does your truth table for (A) equal the truth table for (ABC+AB'C')? Seems to me that they disagree in this case.

It can't really be reduced since you have the factorization
A(BC+B'C')
and the inner term is XNOR which can't be simplified further in terms of sums and products

[Anonymous No.9534130]

>>9534122
Thank you, that makes sense.

[Anonymous No.9534161]

How do I solve this?

[Anonymous No.9534217]

simple error analysis question:
10 measurements were taken, each with a calculated uncertainty of 0.00141. A mean was calculated (0.0225). I'm now asked to estimate the error in the mean. Pic related (top), the standard error of the average value, is in our notes, but so is the bottom method. Which of these methods do I use? It doesn't seem right using the top since that doesn't factor in uncertainty in each reading, but at the same time the bottom method feels convoluted in this instance given the convenient top formula.

Please help, I just spent 20 minutes on paint instead of writing up my report.

I could post the base form from which the bottom equations were derived, but it'd take another 20 minutes. I can hardly remember the error propagation proofs or where it came from.

[Anonymous No.9534226]

pic related might be proper notation (less confusing for mathfags). Be patient, I've barely done any math in college.

[Anonymous No.9534230]

>>9534226

[Anonymous No.9534237]

[Boolean Algebra]

How does one go from X + X'Y to (X' + X)(X + Y)?

I understand that (X' + X)(X + Y) is equivalent as when you distribute it out you get X + XY + X'Y which by the absorption postulate is then equal to X + X'Y.

I just don't get the steps behind seeing X + X'Y and transforming it into (X' + X)(X + Y).

[Also, thanks to those who have been humoring me, I really do appreciate it]

[Anonymous No.9534257]

>>9529678
Brain size correlates modestly with intelligence (0.4 last I checked). How could it not? Larger brains are expensive in terms of calories and causing difficulties in childbirth, so if you could get the same smarts with a smaller average brain size, evolution would shrink brains.

[Anonymous No.9534262]

>>9530557
Think of it as a combination of scaling and a measure of similarity or overlap.

If two vectors are completely parallel to each other, that's the maximum possible overlap, so the dot product is just the product of their lengths.
If two vectors are perpendicular/orthogonal, they don't overlap at all, so the dot product is zero.
If two vectors are pointing in exactly opposite directions, they're "anti-overlapping", so the dot product is the product of their lengths, times -1.
If two vectors are pointing somewhere in between these extremes relative to each other, the dot product will be a weighted combination of their magnitudes and how much they overlap. This manifests as a cosine of the angle between them.

Hope this helps.

[Anonymous No.9534266]

>>9534237
(Not making fun of you this is meant to be an analogy you can relate to...)

How do you go from [math]x^2-4[/math] to [math](x+2)(x-2)[/math]? I understand they're equivalent as when you distribute it out... How do you go from 403 to 13*31? I see that they're equivalent but...

Factoring is just a tricky thing all the time.

[Anonymous No.9534276]

>>9534266
Kek thanks I get it now.

[Anonymous No.9534278]

>>9534237
I mean you basically got it there.

If you want an intuitive explaination, think of what both expressions say. X+X'Y is true if X is true, and if X is not true, it's true if Y is true. (X+X')(X+Y) simpifies down to X+Y, because X+X' is always true.

Now consider X+Y and X+X'Y. For both expressions, they're true if X is true. If X is false, they're true only if Y is true. This is enough to show that they're the same expression, because for any possible values of X and Y they give the same result.

[Anonymous No.9534289]

I'm a tranny in their mid 20s starting an undergraduate degree in mathematics, aware that it's too late to attempt anything outside of statistics.

Am I wasting my time? Should I just quite college attempt to find a beta cs bf who would settle for me?

[Anonymous No.9534304]

>>9534276
One way to look at it might be think about how you're allowed to introduce terms. For instance, you can always introduce XX' in a sum since it is 0. You can use some term introductions like this to do what by analogy might be "completing the square".

We can always introduce x'x and have
x + x'y = x + x'x + x'y
If this were "factorable" into a product of sums we'd have four cross terms between (x, x', y) and one we're missing is xy. But we can see that x = x(1) = x(1+y) = x+xy
so we can turn the lone x term into x+xy giving us
x + xy + xx' + x'y
and the last cross term is just xx which trivially equals x so now our expression is
xx + xy + x'x or x'y
which can be factored

[Anonymous No.9534310]

>>9534257
That's not how evolution works.

[Anonymous No.9534341]

>>9534289
I'm an engineer making decent money, so I think you should drop out and let me pound you. I will require that you enjoy video games and board games like chess or go, and that you know or want to know how to program because we should make math youtube videos and Unity games together.

[Anonymous No.9534350]

Answer please you fucking faggots. This is probably basic for you.

10 measurements were taken, each with a calculated uncertainty of 0.00141. A mean was calculated (0.0225). Calculate the error in the mean. Do I use top method (doesn't account for uncertainty in measurements?), or bottom?

[Anonymous No.9534358]

>>9534310
Why not?

[Anonymous No.9534362]

>>9534350
>faggots
Why the homophobia?

[Anonymous No.9534364]

>>9534350
I forgot pic again

[Anonymous No.9534395]

How do I stop throwing a Kylo Ren tantrum when I don't get the right solution to a problem.

So far I've damaged many of my textbooks from throwing them against the wall.

[Anonymous No.9534433]

Is spivak a meme?

[Anonymous No.9534442]

>>9534395
holy shit friend, just take a deep breath, look at your mistake and do another problem

[Anonymous No.9534584]

So the answer doesnt include the 1/3 before my ln OR any denominator for the inside. ( exact same just no /3). Why is that? I think my answer is technically correct, and i think the rest is just part of the C, but how come?

[Anonymous No.9534748]

>>9534362
Welcome to 4chan.
>>9534395
I have this problem. I keep some kettlebells near where I study. I like to lift them when I get that pissed. Plus the break and exercise is good for you.
g

[Anonymous No.9534753]

Anyone know a good source to learn the basics of weather? I can't find anything in the sticky.
I'm trying to find out more about high/low pressure interactions and how the different -spheres interact. Also the electrical gradient of the atmosphere.

[Anonymous No.9534760]

damn math isnt for me is it

[Anonymous No.9534793]

>>9534760
>can't even write "true" or "false"
lel

[Anonymous No.9534821]

>>9534760
>okay, so...
Kill me

[Anonymous No.9534889]

I'm an Economics dropout. I believe my real interest is in Math, however I have two options: pure maths on an average uni or applied maths on a "high tier" one. What should I do? Pure maths sounds the most interesting to me but applied doesn't sound that bad, at least is not econ.

[Anonymous No.9534912]

>>9534889
>I believe my real interest is in Math
Can you elaborate on why you think so?
>pure maths or applied "maths"
They are completely unrelated disciplines. It's like asking "music or biology?".

[Anonymous No.9534966]

>>9534912
Damn, saying why I like maths is harder than I thought. Well I had never enjoyed a class so much as I did with Linear Algebra. The abstract part of it. How to proof theorems based on axioms. The problems that are solvable using it. Everything amazed me and I believe that if I liked a small fraction of it so much maybe Maths is what I want to dedicate my academic life to.
>"maths"
Yeah I've heard that too and it bothers me but the truth is I don't know much. Any tips on both?

[Anonymous No.9534974]

>>9534584
What is the integrand?

[Anonymous No.9535016]

>>9534974
The integrand is 1/(\sqrt(9+x^2)). Want a picture of my whole process?

[Anonymous No.9535050]

>>9534070
Personally, I dont remember getting taught that, but its essentially just giving different options of how to run through computations from what i see.
I dont know the context in which you guys are learning double and triple integrals, but you just want to take however weird of a (probably simply connected) region and just do the integral the easiest way.
You'll learn later that with your change of variables that you can also get easier substitutions to different coordinate systems (polar and what not) which are orthogonal with respect to themselves, but not necessarily the xy plane.
You sound like you understand it, its essentially just extra words.

[Anonymous No.9535061]

>>9535016
Sure, ill do what i can

[Anonymous No.9535101]

>>9535061
Sorry its such a mess, but its just a pretty simple trig substitution/integral thingy. I just forget the natural log rules so I wanted to make sure my answer is the same as the given answer i posted earlier

[Anonymous No.9535112]

>>9535101
>>9535061
Here made it neater

[Anonymous No.9535160]

>>9527179
PLS HELP A BRAINLET

[Anonymous No.9535179]

>>9535112
I honestly forgot trig substitution, but I looked in my book and found it did that shady think with the constant of integration, the reason why 1/3 doesn’t cancel out on yours log is because I don’t think you plugged it in for dx, best of hope.

[Anonymous No.9535187]

>>9535179
Ohh yea that's exactly what I did, or in this case didn't do. Thanks a ton man!

[Anonymous No.9535238]

math isnt for me is it

[Anonymous No.9535246]

>>9535238
Why aren't you LaTexing your work?

[Anonymous No.9535252]

>>9535246
this is from a linear algebra exam that the professor returned to us via email after photo copying it

[Anonymous No.9535255]

>>9534087
>F = ABC + AB'C'

((A&B)&C) | ((A&~B)&~C)
https://programming.dojo.net.nz/study/truth-table-generator/index

[Anonymous No.9535267]

>>9535252
>this is from a linear algebra exam that the professor returned to us via email after photo copying it
As I said, why aren't you LaTexing your work?

[Anonymous No.9535290]

Physics undergrad, I am looking for a good textbook that covers laser. Post links to pdf file if you happen to have one, thanks in advance.

[Anonymous No.9535293]

>>9535290
Use libgen.

[Anonymous No.9535400]

>>9535293
Thanks, found a goldmine of physics resources :^)

[Anonymous No.9535582]

Do there exist two statements that are true because if either or both are false, a contradiction arises?

[Anonymous No.9535583]

>>9535246
>>9535267
Not him but fuck /sci/'s LelTeX. It still fucks up quite a bit.

[Anonymous No.9535590]

>>9535238
>You pulled this matrix out of nowhere
>Not plainly obvious where the matrix came from

This is some high school-tier shit the professor is pulling

[Anonymous No.9535599]

>>9527189
>Why is there something instead of nothing?
finish a grad course in particle physics and then come back to talk about it
>If God is benevolent, why does he allow the existence of hell?
no god
>How do neurons give birth to consciousness?
inb4 how do letters give birth to words, sentences and books
>If the universe is moving towards chaos, why does life seem so well organized?
random chance
>What is beyond the external wall of the universe?
more universe we can't see yet

[Anonymous No.9535616]

>>9534262
Thank you

[Anonymous No.9535625]

>>9527179
is splitting exponents into groups a retarded way of doing it

[Anonymous No.9535648]

>>9533267
Please help someone, I'm still stuck :-(

[Anonymous No.9535651]

>>9535648
Why do you think an elementary antiderivative exists?

[Anonymous No.9535652]

>>9535625
>is splitting exponents into groups a retarded way of doing it
What do you mean?

[Anonymous No.9535656]

Any advice on how to ace a Calc II class? I'm trying to prepare and don't want to be blindsided by anything.

[Anonymous No.9535658]

>>9535651
It came about when doing a problem and I assumed the previous steps I had done made sense.
Also wolfram alpha came up with a solution when i added the limits, but not without the limits

But I'll have a look and see if I made a mistake up somewhere earlier in the question

[Anonymous No.9535659]

>>9535658
>Also wolfram alpha came up with a solution when i added the limits, but not without the limits
What are your limits?

[Anonymous No.9535660]

>>9535659
0 to 2pi

http://prntscr.com/ii7gn6

[Anonymous No.9535675]

>>9535583
[math]
{{{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}^{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}_{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}}^{{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}^{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}_{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}}}_{{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}^{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}_{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}}}}^{{{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}^{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}_{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}}^{{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}^{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}_{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}}}_{{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}^{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}_{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}}}}}_{{{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}^{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}_{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}}^{{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}^{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}_{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}}}_{{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}^{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}_{{\text{:^)}^{\text{:^)}}_{\text{:^)}}}}}}}}}
[/math]

[Anonymous No.9535684]

>>9535675
Ha gay

[Anonymous No.9535765]

Where can I find exams questions for Statics? I'm using the Hibbeler book recommended by the wiki

[Anonymous No.9535832]

>>9535160
Does anyone know anything about signals?

really struggling with this

[Anonymous No.9535883]

>>9529678
>what is encephalisation

[Anonymous No.9535898]

I've row reduced this matrix:
[math]\left( \begin{array}{ccc}
0 & 1 & 3 & 1 \\
1 & 2 & 6 & 1 \\
0 & 1 & 6 & -1\\
2 & 2 & a & b \end{array} \right)[/math]

To the following:
[math]\left( \begin{array}{ccc}
1 & 2 & 6 & 1 \\
0 & 1 & 3 & 1 \\
0 & 0 & 3 & -2\\
0 & 0 & a & b \end{array} \right)[/math]

By these steps:
Interchange R1 with R2.
Replace R4 by subtracting R4 with 2 times R1.
Replace R3 by subtracting R3 with R2.
Replace R4 by adding R4 with 2 times R2

I don't feel done, but what more can I do here? I'm just supposed to get it to echelon form.

[Anonymous No.9535902]

Sorry, I meant augmented matrix. Last column is the right hand side of the equations.

[Anonymous No.9535909]

>>9535898
>I don't feel done, but what more can I do here?
Reread what RREF means.

[Anonymous No.9535921]

>>9535898
R2 -= R3
R1 -= 2*R2
R1 -= 2*R3
R4 -= a/3 * R3

[math]
\left( \begin{array}{ccc} 1 & 0 & 0 & -1 \\ 0 & 1 & 0 & 3 \\ 0 & 0 & 3 & -2\\ 0 & 0 & 0 & b+2a/3 \end{array} \right)
[/math]

[Anonymous No.9535929]

>>9535921
Thanks. Seems obvious now.

[Anonymous No.9535931]

Came across this in a practice exam for the medicine admissions test. My maths isn't great.
[eqn]E^2=(m^2.c^4)/(1-[v^2/c^2])[/eqn]

if [eqn]v = 1/2c[/eqn] why does [eqn]E = (2m.c^2)/√3[/eqn]

[Anonymous No.9535933]

>>9535931
oops, kind of fucked up the syntax.

[Anonymous No.9536144]

Answers sci? Preferably with explanation

[Anonymous No.9536147]

Also having trouble with D

[Anonymous No.9536148]

>>9536144
>phonefag

[Anonymous No.9536153]

>>9536147
P(x<=4) = 1 - (P(x=5) + P(x=6))

[Anonymous No.9536170]

>>9531774
because we have 10 fingers

[Anonymous No.9536601]

Dumb question about complex exponentials:

I was told that you can prove the sum/difference/double angle identities using complex exponentials, and that the proof goes something like this:
[math]
e^{i\theta} = \cos(\theta) + i \sin\theta\\
e^{i \cdot 2\theta} = ( \cos(\theta) + i \sin\theta)^2\\
\cos^2(\theta) - \sin^2\theta + 2i \sin\theta \cos\theta\\
\text{REAL} = \cos^2(\theta) - \sin^2\theta \\
\text{IMAG} = 2i \sin\theta \cos\theta\\
[/math]
And for some reason, we just ignore the imaginary part. Can we do that? Or am I missing something fundamental about this.

[Anonymous No.9536614]

Will this be an addition reaction?

[Anonymous No.9536642]

>>9536601
did you forget to square the i?
i^2 = -1 so it isn't imaginary in that case

im probably wrong, but im too lazy to check

[Anonymous No.9536649]

>>9536601
The real part is [math]\cos \left(2\,\theta\right)[/math], and the imaginary part is [math]\sin \left(2\,\theta\right)[/math].

[Anonymous No.9536654]

>>9536601
you cancel the i's. if i*sin2x=2i sinx cosx, then you can conclude sin2x=2sinx cosx.
but doesn't de moivre's identity use the double angle identities in its proof anyway? so youre already assuming the conclusion.

in linear programming, when converting between min and max, which is correct (or are they both):
maximum c^T x=−minimum (−c^Tx) or
maximum c^T x=minimum (−c^Tx) ?
i'd assume the first, but i've seen many books with the second.

[Anonymous No.9536657]

Why don't countries invest into asteroid mining and create a monopoly on a specific material such as Gold, Silver or Platinum

[Anonymous No.9536687]

>>9536649
Oh! That makes sense!
[math]
e^{i\cdot 2\theta} = \cos(2\theta) + i\sin(2\theta)\\
\cos(2\theta) + i\sin(2\theta) = \cos^2(\theta) - \sin^2\theta + 2i \sin\theta \cos\theta\\
\text{And because REAL(LHS) == REAL(RHS) and IMAG(LHS) == IMAG(RHS)}\\
\cos(2\theta) = \cos^2(\theta) - \sin^2\theta\\
\sin(2\theta) = 2i \sin\theta \cos\theta\\
[/math]

Okay. That makes a lot of sense now.

[Anonymous No.9536699]

what the fuck is an electric flux? this is a reply from leddit

>You might find it easier to understand in this way: The net electric flux of a closed surface is the total amount of E field lines penetrating the surface and going inside the "volume". Something with positive net flux means that there is more lines going into the surface than leaving the surface. Vice versa for negative. In the picture, looks like for every E field line penetrating into the surface on the left, there is an equal amount of E field lines penetrating and leaving the surface on the right.
this is bullshit right? then how come the flux going through a sphere is positive? what the fuck is a Gaussian sphere?

[Anonymous No.9536708]

>>9536614
h...help

[Anonymous No.9536717]

I really enjoy the program functionality of my TI83.

Currently, my equation is thus:

r = [4h^2+L^2] / [8h]
L = length of curve, h = distance from middle of a chord to the outside edge of the curve
This allows me to calculate the radius of a curve without leaving the curve itself. Quick aside, this is for making forest roads and finding out the various features in play therein.

Is there an app that allows me to reach this equation and subsequently store it in an easy-to-use fashion? Currently my TI83 asks me to put in "h", then put in "L", then it gives me "r". I want an app that goes exactly this for whatever function I choose to save. It asks me for the variables one at a time, I tap them in (or leave them as an unknown in order to solve for that variable if possible), and it gives me the answer.

I've gone through about 5 different apps so far and none of them have the same functionality as the TI PRGM. Any suggestions?

[Anonymous No.9536738]

>>9531774
In 1624 Briggs published his Arithmetica Logarithmica, in folio, a work containing the logarithms of thirty thousand natural numbers to fourteen decimal places (1-20,000 and 90,001 to 100,000).
Easy to work with historically.

its all about natural logs once you start calculus

[Anonymous No.9536749]

>>9535656
Read the book before they touch the material in class.

[Anonymous No.9536759]

Alright, bombed my linear algebra test.
What is LU factorization for? It seems so tedious, and you end up row reducing everything anyway, why not just rref the original matrix?

[Anonymous No.9536791]

>>9536717
why not just learn to program a computer?

[Anonymous No.9536793]

I want to improve my basic electronics knowledge and circuit creation, including soldering. Does /sci/ know of any kits that do the job, similar to Arduino/Raspberry Pi for programming?

[Anonymous No.9536993]

What is the meaning of life?

[Anonymous No.9537001]

>>9536993

[Anonymous No.9537052]

>>9527179
I tried to follow the way this guy applied the Stefan-Boltzmann law to find the temperature of the sun, but I can't get the same answer.

https://www.youtube.com/watch?v=WkzMgsTLDfs&index=3&list=PL9676E709CDDE1FCD

I thought he just forgot to explain that you need to take the 4th root of his final equation, but even when I do that, I only get around 1000 K instead of the 5700 K that he got.

Am I retarded, or is he retarded?

[Anonymous No.9537274]

>>9536791
Because I can't carry a computer in my pocket.
If only such a thing was possible!

[Anonymous No.9537281]

>>9537052
just did the calculation myself and also got 5700
did you remember to square D and R?

[Anonymous No.9537285]

How to do number 3?

[Anonymous No.9537442]

>>9533148
It's the relational inverse of the function.