/sci/ - Science & Math

After AGI being invented, can all of us people have basic income?

>>10343661
Find time required to reach the specified height.

How can I build muscle? I can't build muscle

>>10344070
SS+GOMAD

>>10344070
by being straight

my question is related to (i)

>>10344338
Okay how’d I do?
I’m pretty sure I proved the two conditions necessary for something to be a basis for a topology. However my classmates say I’m incorrect because I didn’t prove all 3 properties of a metric. However I disagree because I am given the literal metric in the definition of the thing that I want to prove to be a basis. Yes a metric defines a topology, but that’s not what the question is asking. Am I correct in my thinking or do I need to do more? Is proving a metric on a topology equivalent to proving something is a basis for a topology because I dont think so

bump

Need some help with statistical physics, specifically with moments/ cumulants and how to get them from a partition function.
Lots of my problems are of the way where you have to find a partition function for a given system, and then eventually calculate some expectation value or variance of sorts, and I feel like getting them through the momenta generating function is a simple way that should pretty much always work out, but I always have trouble with my variables...

Say I have a grand canonical ensemble with a partition function [math]Z = \sum_{N=0}^{\inf} exp(-\beta H)[/math] where [math]H[/math] is a function of particle count [math]N[/math], chemical potential [math]\mu[/math] and maybe in general just a bunch of parameters like that.
I know that the moment generating function for a random variable [math]X[/math] is defined as [math]M_X(t) = \sum_{x \epsilon \omega} e^{x t} p_x[/math] for discrete distributions (like spins and shit) or with an integral for continuous stuff.
Now my first problem is how do I get [math]p_x[/math] or[math]p(x)[/math] from my partition function? There must be a way since all the information should be in there, but my script and anything Ive found doesnt provide a straight forward relation. One physics stackexchange post mentioned [math]p(x) = \frac{Z(x-t)}{Z(x)}[/math] but I dont know where that comes from and it didnt work in one problem I tried to apply it to.
And then when it comes to actually computing the momenta I know that you have to derive with regard to t so that [math]<X^k> = \frac{d^k}{dt^k} M_X(t)[/math], which I also dont quite understand, because in a lot of the solutions to problems the take derivatives with regards to things like [math]\beta[/math] if they want mean energy (I think) or [math]\mu[/math] if they want mean particle count, which sort of looks like the moment approach, but instead of the meaningless variable [math]t[/math] they use these things that have actual physical value...

Medfags,
I have an interdigital mycosis (like pic related, but on my right foot) and I just got myself some antifungal powder to treat it and disinfect my shoes
I'd like to know, should I take any particular hygiene measures additionally to the treatment?
I've already changed by bathing towel, should I also change my bedsheets and other stuff?
Also, can that kind of mycosis spread to the hands?

>>10344340
I can't read your chicken scratch.

today my teacher said that chlorine adams want to gain an electron to complete their octet. she said that this makes them more stable and have a lower potential energy. However, this makes the charge of the chlorin(d)e -1. Wouldnt it have lower potential energy if it had a neutral charge? Doesn't it have electric potential now?

She said something confusing when I asked, but she also says that every calculator is a little different whenever she makes a mistake.

>>10343783
If you have 100 rats who are black or white. They either eat corn or don't eat corn. 60 of them are black. 20% of the white ones don't eat corn. And 70% of them are either black or eat corn (not both). What's the conditional probability that a rat eats corn given that she is black?

>>10344642
You can use a decent probiotic, hydrate the insides and spread it on the area. Candidiasis usually happens when other biota die off and candida takes over.

You could also try some ketoconazole shampoo on the area, leave it on 10 minutes and rinse off once a week.

>>10345054
Alright, thanks.
Should I be careful with what touches the affected area? I ended up changing my bedsheets but I'm wondering if it can spread to my hands too if I'm not careful.

>>10345005
Work out the percentage of black ones that don't eat corn. 60% are black (black pop/total pop), 40% white, 20% of forty percent is 8% that are white and don't eat corn, 32% are white and eat corn. 70% are black and don't eat corn or white and do eat corn, meaning 70% - 32% = 38% are black and don't eat corn. So (60-38)/60 is the probability of eating corn given black.

>>10345059
I don't know enough about why you might have the condition. Candida's everywhere, you may have picked up a more aggressive strain, you may be more prone for some reason to contact with candida and it grows differently on you. Speak to your derm.

>>10345005
Draw a rectangle, and trace a line across the middle. Write B on one side to signify its black, and W on the other for white. Draw a circle in the middle that's also divided by the line and marm that the space inside the circle is for rats that eat corn, and outside is for those that don't. Then try to fill the data up.

>>10345071
I don't hang around public pools or whatever, I probably picked it up from humidity in my own shower or wearing thick as fuck socks this winter.
I'll go to the derm next week, I just can't find much info on whether that kind of fungus easily spreads to other areas besides the feet generally speaking.

Is there like a list of all tricks and heuristics to solve integrals?

Sorry for the brainlet question in advance, I'm not sure what does
[math]f^+=max(f,0)[/math]
and
[math]f^-=max(-f,0)[/math]
mean, I'm guessing the positive and negative part of a function respectively, but I'm not sure on why its noted with [math]max[/math]

>>10345250
why dont you draw an example

>>10345250
[math]f^+[/math] is a function that's equal to f whenever it's positive, and equal to zero whenever it's negative.

>>10345171
no, but there are quite a lot more than you learn in class:http://gen.lib.rus.ec/book/index.php?md5=3D18AD7338921F88C9AA2B42CDB8D7FF
http://gen.lib.rus.ec/search.php?req=irresistible+integrals&open=0&res=25&view=simple&phrase=1&column=def
https://www.tapatalk.com/groups/integralsandseries/
http://gen.lib.rus.ec/book/index.php?md5=194C85BBB944BC18B99E23AC5B2C33DB
http://gen.lib.rus.ec/book/index.php?md5=2DE7C39495F25F840679EFE5B602CD1D

If the quantum field theory says that gravity is just fluctuations in a single gravity field that permeates the entirety of the universe, and the same with electromagnetism, is matter also just a field?

question on semantics
is the Lie bracket the bilinear map VxV->V by (v,w)->[v,w] or is it the image of this map [v,w]?

>>10343783
Yui is so cute

>>10344070
The more you post about not building muscle, the more muscle mass you lose. Like cardio.

>>10345171
ask cleo
https://math.stackexchange.com/q/563063

>>10344070
Whining on 4chan all day every day is not how you get muscle, I can tell you that much.

>For every real ε > 0, there exists a real δ > 0 such that for all real x, 0 < | x − p | < δ implies | f(x) − L | < ε.
wat

>>10345492
describes the limit L of the application f when x tends towards p

>>10345171
it's in czech tho lol
http://math.fme.vutbr.cz/download.aspx?id_file=155514382

If I have an ideal I in a finitely generated ring R, how do I show that R/I is flat as an R-module if I=(e) for some e with e^2=e?

anyone happen to know any slow, non toxic Co2 or O2 producing reactions?

Specifically need to increase the PSI in a 7 gallon, room temperature carboy from 14.2 to 25-30 over a long enough time to not kill any insects.

>>10345372
the map

>>10344175
I already am and this didn't help
Maybe I have a woman's body and am unknowingly a lesbian? I thought about it but don't know how to check for sure.

>>10345414
Good thing I don't do a lot of cardio, so I can indulge in posting on /sci/

>>10345475
I know, but not doing it didn't help either. I'm desperate at this point since nothing works and life isn't worth living if you can't build muscle

>>10345823
Go to the gym and ask someone to train your dumb ass. Also watch Jeff Cavaliere on youtube

>>10345841
I have already been coached. When I told him I couldn't build muscle he reacted like you thinking everybody can build muscle, but at the end he was like "well I know people who can't build muscle either" (i.e. he doesn't know anyone who can but pretends to do so to make me feel better, yet still acknowledges that I can't build muscle)

>>10345844
anyone who can't*

>>10345844
Then go to a doctor and ask them to check you for anything weird with your hormones or muscles or whatever

>>10345901
They just tell me "not everybody can be Arnold", then I tell them I can't build muscle *at all* and they just say "well, not everybody can...". Basically any problem thats not life threatening is treated with "I know somebody who has the same problem so it invalidates said problem". They are blue pilled cunts I hate them. I want a doctor that will acknowledge that it is a terrible issue for a man. I mean, there are disgusting degenerate faggots who get full sex changes funded with my own taxes but when I can't build muscle it's not a problem. Kikes ruined everything in the western world

>>10345004
Chlorine, much like every halogen atom, get more stable one they accept an electron in their valence shell. In the case of Chlorine, tye explanation you could give is that it makes Chlorine respect the octet rule. However, it's also because a lone electron, next to paired electrons, is not so stable and would much prefer have another electron with an opposite spin.

>>10345907
Tough shit then

>>10345298
I don't know much about subatomic particle physics, but what I do know is that electrons act both as a wave and as a particle.

>>10345678
good thing I'm actually trying to pick up some czech lol
dekuji

>>10345695
It's enough to show injective R-module homomorphisms [math]V \rightarrow W [/math] go to injections [math]V \otimes R/I \rightarrow W \otimes R/I[/math]. Use the fact that [math]V \otimes R/I \cong V/IV [/math].

>>10345955
thank you, I was aware of the facts you showed, but I do not see how they help me. Could you elaborate?

How do I show that the characteristic of a field is prime? Some proof online went as follows: Let n = ab for a>1, b>1. Then n1 = ab1 = ab = 0, so either a = 0 or b = 0, and the proof follows. I don't understand it. n isn't zero to begin with, so how is this proof solid?

>>10346069
Lemma one: a field has no zero divisors.
You can trust me, or you can prove it on your own.

>>10346080
I got it. The thing is is that this is for a graduate level linear algebra class, and a decent chunk of the class (including me) haven't taken abstract algebra. This nigga is asking questions like "Give an example of an infinite field with positive characteristic" and "Show that Z cannot be a vector space over any field" on the first homework. We're not even far enough into the book (Halmos) for me to wipe my ass with the pages, and I'm shitting myself. Speaking of that, how do I show that the set of rational polynomials with prime coefficients has positive characteristic?

If I have a continuous function in a closed interval and |f| is absolutely continuous do I have that f is also absolutely continuous? I want to believe it is since |f|' exists almost everywhere so at worst f' will exist whenever there isn't a change of sign.

>>10344338
Notice [math]d(f,g) = \int_{[0,1]}|f-g| [/math] defines a metric on [math]C^0([0,1]) = C[0,1][/math]. Think of [math]\mathcal{M}(f,\epsilon)[/math] as balls of radius [math]\epsilon[/math] centred at [math]f \in C^0([0,1])[/math].
>>10344451
The probability distribution is the Boltzmann factor [math]p(x,N) = e^{ -\beta (H(x)-\mu N)}[/math]. Let [math]X_N[/math] denote the configuration space of [math]N[/math] particles with sigma algebra [math]\Sigma_N[/math] defined by Borel subsets of [math]X_N[/math], then [math]p:\coprod_N \Sigma_N \rightarrow [0,1][/math] defines a probability distribution.
This leads to the fact that the [math]n[/math]-point correlation functions [math]\langle x_1,\dots,x_n\rangle[/math] can be written as [math]\frac{1}{Z}\operatorname{tr}(x_1\dots x_n e^{-\beta(H-\mu N)})[/math].
>>10345298
First of all QFT does not say any such thing. Gravity is the fluctuation of the metric about [math]\eta_\mu^\nu[/math]; it's basically the theory of principal [math]\operatorname{Diff}(M)[/math]-bundles on [math]M[/math]. Second of all the fact that matter are fields does not originate from gravity; matter fields have been studied ever since the inception of QFT in the 1920's as operator-valued distributions. It'd do you well to read an actual QFT book.
>>10346585
Write [math]|f|[/math] as [math]f^+ - f^-[/math] and you can show both parts are absolutely continuous by restricting to their disjoint supports. Then reconstruct [math]f[/math] as [math]f^+ + f^-[/math] and viola, you're done.

>>10346593
Okay, I completely overlooked that decomposition. Guess it's time to hit the sack, thank you for your trouble.

>>10346593
>viola
I too browsed /lit/.

Are the following statements correct? If not, what should I

Assuming you don't win or lose anything based on the outcome...

1. if you roll a fair 100 sided die untill it has stopped moving, the odds of it landing on a single specific side are 1 in 100.
2. if you roll a fair 100 sided die and stop it with your hands, the odds of it landing on a single specific side are 1 in 100.
3. if you roll a fair 100 sided die and it bounces off a wall, the odds of it landing on a single specific side are 1 in 100.
The real problem:

1. I have 1 highly educated person (masters in physics/compsci) telling me this is wrong
2. I have 1 highly uneducated (barely scraped by highschool) person telling me this is wrong.
3. Most important: I want to know, but the educated person says they're too tired to explain it
4. Searching about this gives me basic highschool permutation/combintation stuff that serves my belief, but I don't know enough about math/stats to know for sure this is correct or that I'm searching the right stuff. It could be that this is just a basic intro and I'm missing more advanced concepts.


Bonus!!!

What is more likely:

1. The uneducated person being highly educated on this topic
2. The educated person being uneducated on this topic
pls help im retarded and want to know

>>10346593
Thank you

How to deal with anxiety before exams and other important stuff? This is slowly killing me inside and I don't now what to do.
Nootropics is not an option.

>>10346611
wa la

Does anyone know where I can find a good resources on Galilean relativity with some questions to do? Our lecturer has given us an assignment with 3 questions on speed of objects and positions of objects in different reference frames and said "I assume you all know this so we won't go over it too much detail". I don't know it.

>>10347344
They happen so regularly that you will get used to them eventually.

>>10347358
A Galilean transformation is literally just an affine transformation followed by a speed boost.

So if you want to move the frame [math]Oxy[/math] to have origin [math]P=(a,b)[/math], then do the change of variables [math](x,y)\mapsto (x+a,y+b)[/math].

If you want to scale/rotate/shear/reflect the frame, this is equivalent to multiplying by a 2x2 matrix with non-zero determinant, ie [math](x,y)\mapsto (ax+by,cx+dy)[/math] with [math]ad-bc\not=0[/math].

If you want to boost a frame with speed [math](v_x,v_y)[/math], you have the map [math](x,y)\mapsto (x-v_xt,y-v_yt)[/math].

How the fuck cloths dry? Water boils at 100 Celsius when room temperature is ~20 on average, it doesnt make sense

>>10347601
same reason that if you leave a glass of water out overnight, the cup will have like 10-20% less water when you wake up. Evaporation is the word. You don't need a liquid to boil for it to evaporate.

>>10347611
So why water evaporates, evaporation needs a lot of energy to change the state of the liquid to gas, where the fuck this energy to free the bonds comes from

>>10347620
It follows from simple molecular theory. Imagine you have water in a glass again. There is a distribution of energy in the water, with some having very high energy, and some very low, but on average they have medium energy. These very high energy particles can "break" the bonds of the water and escape into the atmosphere. Similarly, high energy particles from the air might hit the water molecules very hard and pop them out of the glass.

If the room is well ventilated, the glass of water will eventually fully evaporate.

Identify this

>>10348016
Serotonin

>>10343783
Is that burd gonna be OK?

Can someone fucking thell me where R2 went? I know how to use the superpositional technique or how it's called but R2 ans R1 are supposed to be in a series when I remove the power source I1. I need to find out which power's between A and B when I'm only using U1.

>>10348169

What's the general idea behind doing x * x.T * x for a given row vector x? Is there a name for this construct?

>>10348198
x.xT is ||x||^2, i.e. the square of the magnitude of x. x.xT.x is ||x||^3*(x/||x||), i.e. it has the same direction as x but with the magnitude cubed.

>>10348198
thanks, makes sense

Hey /sqt/, i have a function [math]P(x)=x^5+x+1[/math], and i need to prove that its surjective on the reals, i think that if i prove that [math]P(x)[/math] is continuous on every x, then it would imply that for every x there's at least a F(x) for it.

I tought on separating the function such that
[math]f(x)=x^5[/math], [math]g(x)=x[/math] , [math]h(x)=1[/math]
Then prove continuity on each such that if [math]f,g,h[/math] are continuous then, by theorem
[math](f+g+h)(x)=P(x)[/math] is also continuos, making [math]P(x)[/math] surjective
I guess i could also use delta-epsilon definition on [math]P(x)[/math] and spare me some steps.

>>10348668
I don't understand what you want to say.
[math]f(x) = x^2[/math] is continuous but it is not surjective on [math]\mathbb{R}[/math]
Where does [math]f(x)[/math] go as x goes to [math] \plusminus \infty [/math].
Combine that with continuity.

>>10348668
First of all, [math]P(x)=x^5+x+1[/math] is surjective if and only if [math]Q(x)=x^5+x[/math] is surjective (proof left to the reader), so you don't need the h.
Secondly, every polynomial is continuous.
Third, exploiting the intermediate value theorem requires you to show that it's unbounded. There's an easy trick to do that involving the f(x)=x function.

>>10348683
I thought that by proving that each point was continuous, and defined, then it would mean that for every P(x) there is at least one x in the domain. If P(x) was discontinuous in some point, then it would mean that there's an P(x) which has no x that produces its output, thus making it not surjective.
Is [math]f(x)=x^2[/math] not surjective? I thought that it wasn't injective but it was surjective.
>>10348686
So i don't need continuity to prove its surjective, and not every continuous function is surjective. And i'm lost on your third point, how can i use the intermediate value problem to show it's surjective?
Thanks for the responses, i appreciate the help and i'm sorry for the brainletism.

>>10348827
No? Try finding a number whose square's negative.

>>10348668
I don't know exactly what you're allowed to use here, but the argument is easier than you think. Polynomials are trivially continuous. I wouldn't think you'd need to prove this, but if you do, just prove it for a monomial [math]x^n[/math] and then use the fact that sums of continuous functions are continuous.

First step in the argument is that [math]x\to\pm\infty \implies p(x)\to \pm\infty[/math]. You can do this by approximating [math]p\approx x^5[/math] in a rigorous way, and it holds trivially for [math]x^5[/math].

Second step is to recognize that for any two real numbers [math]a,b[/math], there exists a compact set [math][n,n][/math] that contains them, where [math]n=\max\{|a|,|b|\}[/math].

Third step is to use the intermediate value theorem, which states that for any continuous function on a compact set [math][-a,a][/math], the function takes all values between [math]f(-a)[/math] and [math]f(a)[/math].

You can now conclude surjectivity: Let [math]a\in\mathbb R[/math]. We want to show it is in the image of [math]p[/math]. Since [math]p[/math] in unbounded, there exists [math]y,z\in\mathbb R[/math] such that [math]f(y)<a<f(z)[/math]. Then choosing the compact set as before, we can apply the intermediate value theorem to show every value is attained between [math]f(y)[/math] and [math]f(z)[/math], in particular, there exists some [math]x\in\mathbb R[/math] such that [math]f(x)=a[/math].

QED

>>10348957
**Correction: compact set should be [math][-n,n][/math].

>>10348957
**correction 2: should have written [math]p(y),p(z)[/math], etc, not [math]f(y),f(z)[/math].

To add to that this argument doesn't just work for that polynomial, it works for all odd polynomials, and more generally, for all continuous functions on all of [math]\mathbb R[/math] that are unbounded both ways.

>>10348942
>>10348957
Thanks a lot for the responses, turns out i forgot to read a couple VERY important theorems for continuity.

>>10343783
basic math question: I was solving 2x^2 - 3x - 4 by using the quadratic formula, but how come wolfram alpha says you're supposed to do 3/4 + sqrt(41)/4 instead of just doing 3 + sqrt(41)/4

sorry 4 being gay

Any astronomers lurking?
How would life on Earth be different if it had a 28-hour rotation cycle instead of the (roughly) 24-hour cycle it knows now?

>>10349174
The quadratic formula is (-b +/- sqrt(b^2 - 4ac))/(2a). The 2a divides the whole numerator, not just the second term.

>>10348668
Hint: all odd-degree polynomials in [math]\mathbb{R}[x][/math] have a root in [math]\mathbb{R}[/math].

>>10349400
Not an astronomy question. The main difference is that the daily temperature cycle would have greater variation: longer days, longer nights = hotter days, colder nights. So mainly an issue for biology/ecology/climatology.

>>10349400
it would modify creatures circadian rhythm and with it a lot of biotic interactions and evolution. So probably a bit different in some nocturnal life adaptations, but maybe not that much tho.

>>10349918
>>10349932
Much appreciated, fellas. I like hearing from other perspectives.

Reposting from /g/ since this board feels more academic in nature:

I'm currently completing a BS in computer science and I was wondering what are the best electives to take.

The electives I plan on taking are:
>networks
>computer security/cryptography
>databases
>computer graphics
>intro to artificial intelligence
>intro to machine learning

Does this seem like a good selection of classes or are any of these classes not that great to take?
I was thinking about fitting in software engineering but wasn't sure what to replace with it. Would SE be worth taking? It feels like something I'll learn at a job anyways.
What are the best computer science electives someone should take? Note: compilers and operating systems are already required to take where I go.

>if n^2 is even n is even
how the fuck is this true? n^2 = 6, n is clearly not even, let alone an integer.

>>10350562
Obviously n is assumed to be an integer

>>10350562
lmao how do you even write 6 as a square of integers lmao you cant sit down boy

is there any code source that makes a neural network without importing some plugin so that trying to understand the network from the code becomes meaningless

i've been figuratively banging my head because these fucking ML blogs think seeing a neural network done in 10 lines is gonna help me learn what the fuck is actually going on

>>10350578
no wonder, my prof didn't include that in the power point.

>>10350562

Just a quick question in regards to Discrete Mathematics, to make sure I'm understanding this Venn Diagram correctly. If I'm given area U, and the equation A - (~B), then the area that it's referring to is nothing at all, right? Because you're subtracting from A everything that isn't inside B, which is everything including A.

>>10350872
No, it's referring to the intersection between A and B, actually.

>>10350877
ohhhhh. It's roundabout way of interesection. Tricky bastard. Thanks.

>>10345907
Woah there boiii you sound angry afffffffff xDDD

On a serious note, tell your fucking doc to send you to an endocrinologist to check up your hormones, you seriously might have something wrong with you. You might have klinefelters or some shit. If something's wrong with your hormones, which is a possibility, you can get test therapy that sadly lasts your whole life if you decide to go down that route since your body doesn't naturally produce the necessary amount of hormones, but in turn you can actually build muscle.

Either that, get a new doc, or see a doc privately (by that I mean pay up in a private clinic) to get your hormones checked. Your best bet tbheich

So I was checking the kitchen stove at my parents' house because the flame was coming out all orange. Well actually it was coming out blue then turning orange at the tip. Did some googling, read something about humidifiers messing with that. I turned off their ultrasonic humidifier and sure enough a while later the flame is all blue. If you place the humidifier right next to the stove and turn it on the flame becomes bright orange almost instantly.

I imagine ultrasounds are somehow messing with the airflow around the burner but how does this effect happen several meters away and through several walls?

>>10343783
Here's an autistic one:
If someone's good enough at math, could they have the ability upon looking at an equation to immediately tell what it's about? Taking into account they're familiar with the notation of the particular equation.

Let me elaborate further: what I'm actually asking is, does every equation in mathematics must have a meaning? Like, (2+4)/3=2 reads a third of the number in brackets is 2. It's a simple equation, but its literal meaning is the third of some number.

I don't know if I can put this into words well enough, what I want to say is, you can look at some equations and know what they're about, but some are so complicated you are basically presented with a tool to use, you plug in some variables, and you get the desired result. What I want to understand is the tool. When things get to abstract they seem to lose meaning to me.

I actually don't understand what I don't understand about math. I'm looking way too deeply into it. I'll reply to myself if I find a good example of what I mean.

>>10350917
You're asking if there is some sort of universal meaning in math that tells you what an equation is even if you've never seen it before? Like if an alien could somehow read human symbols could it look at say the time dilation formula and know what it's all about?

>>10350917
No, because it's somewhat contextual.
For example, x=f(x) can be seen as a restriction of a set X to the members mapped to themselves by the function, or it could be the definition of the function f(x), or it could even be the statement that for an element x, f maps it to itself.

Hi, I don't get why we must find Px = mg * sin(alpha) in such cases.
Someone could explain me please?

>>10350877
If you're still here, I've got another question for you on the subject of Discrete. How would you go about finding the intersection of three sets, when you know every other permutation of the three sets? I can't get the Inclusion-Exclusion Principle to work correctly without knowing what it is I need to exclude.

>>10350975
The intersection of A, B and C is equal to the intersection of A with the intersection of B and C.

>>10350978
... It's always so much simpler than I make it in my head. Thanks again.

fucking how do i find these velocities this is fucking retarded

>>10350961
We have a force vector. The problem is, it points straight downwards, so we don't really have any proper use for it.
So we decompose it into its two main parts: the one that effectively causes motion (i.e. points in the direction to which it accelerates) and the one that produces attrition (in other words, points against the force and equals the normal force on the block).
With the former, we calculate the initial acceleration, and with the latter the attrition. Using these two nets you the actual acceleration.
>>10351240
Proportions.

>>10350961
Because you're assuming that the block is moving, and are modelling thereafter.

>>10350897
No shit I'm angry, the last doc I saw was like "Do you practice swimming", ????? "Because that's how you build muscle, look at the athletes that compete in swimming!" But... these guys go to the gym "No, no, they don't, they just swim for hours!". That's literally the level of doctors in France, who make on average like 10k€ a month to spit this bullshit. Of course, I won't get a prescription for getting my T levels checked until I waste my time trying his stupid suggestion of spending several hours a day swimming in the hopes of building muscles. And he'll get mad at me for suggesting he's fucking stupid too. I mean, what can I do now? Fucking kikes ruin everything. Why can't I build muuuuuuuuscle why why why. I'm not even sure it's possible in my country to pay privately for health related stuff like checking T levels or getting a karyotype scan done to check for Klinefelter's

>>10343783
How do the genetics that determine penis size translate into females?

This question is half for comedy but I'm also curious about this.

>>10351261
>Proportions
elaborate further please
ive tries with L/2, M/2 (as the middle arrow is meant to be for the middle of the rope, I forgot to label it), both of them at the same time , Ive tried T = 0 (which results in the velocity being 0)

>>10343783
What the fuck does smol mean, nigger?

>>10351408
The size of my muscles after years of training

Can anyone calculate the chance that can't build muscle poster is the same guy who posted the pasta about people replying seriously to memes?

>>10351528
What pasta? Can't build muscle guy here, I'll give you an answer

>>10351528
>guy who posted the pasta about people replying seriously to memes?
that was actually me, i dont like the muscle guy, i think he's the same tranny making bad sqt threads
>>10351545
its along the lines of "why dont sci posters...."
ive only posted it once and someone started spamming it

>>10351556
I meant the guy who spammed it, not the original poster.

>>10351556
I have never created a single thread but I can start if you want

>>10351564
oh, then I have no clue
>>10351565
please dont

>>10351568
tell me how to build muscle and if it works I'll never post again

>>10351576
/fit/ has honestly ten times more and ten times better advice than we do.

>>10351581
I have already visited this board time and again, none of their pieces of advice are useful. They just have good genetics. I want to know how I can build muscle with bad genetics

>>10350950
Yeah, if he understood the concepts, and the relations, and the background of it. I can't tell what the fuck is going on in more difficult equatinos, they seem way too abstract and I can't understand their derived meaning. I guess that's what Im asking about

>>10351306
You can most definitely, since I can do it in an even shittier Balkan country. I have the same problem as you, going to the gym yields next to no results. it's probably the way you're built, but I'm telling you google it a bit and see where to get your T levels checked. Not sure about the cost of it in France, but it's fairly cheap here.

>>10351850
Did you go to a doctor and get a diagnosis? How did you fix it? What were your lifts after, say, a year or whatever time span you spent lifting? If it's the way I'm built then it's going to need to be fixed, whatever the costs or implications

>>10350917
What you're trying to describe are polynomial equations, sort of. Equations don't have to describe anything necessarily tangible whatsover.

For example, the equation x^3+x=3 literally just means, I have a number and I cube it, then I add it to itself and I get 3.

Polynomials are just a glorified/practical way of representing the usual operations like adding, subtracting, multiplication and division.

>>10351424
im starting to like this meme, not gonna lie

2x^2-1=0
2x^2=1
x^2=1/2
x=sqrt (1/2)

So how the fuck does this actually equal sqrt (2)/2?

What did I do wrong here? I was suppose to find the general solution

>>10352682

Square root of (1/2), root(2) on 2, and 1 on root(2) are all equivalent.

>>10352858
Oh, well that's annoying because khan academy doesn't accept it as an answer

>>10352682
√(a/b)=√a/√b
√(a*b)=√a*√b
√a*√a=a
√(1/2)=√1/√2=1/√2=√2/(√2*√2)=√2/2

>>10352885
The usual convention is to use the form a√b/c where b is square-free and a,c have no common factors. So √(a/b)=>√a/√b => √(a*b)/b then move any square factor of a*b outside the radical: √(p*(q^2))=q√p.

>>10352809
The fuck is up with the piss lighting?

>>10352959
Thx anon

>>10351927
Back up a couple of steps. How much are you eating?

>>10352959
>[math]\color{#e3be15}{y' = \frac{-u^{-3/2}}{2}}[/math]
should be
>[math]y' = \frac{-u^{-3/2}}{2} u' [/math]

How the fuck do I learn about circuits? I can't understand and fucking anything.

>>10353144
Manga Guide to Electricity

>>10343783
I am just starting to learn how to diferrentiate.

an exercise tells me to to show the quotient on time interval [0;Δt] is 5 * Δt
for function s=5t^2

Can someone explain what is ment by a interval from 0 to Δt

>>10353366
s(t) = 5t^2. The difference quotient of s on an interval [a, b] is (s(b) - s(a))/(b - a). In your problem, a = 0 and Δt is the difference in time between the endpoints of the intervals i.e. Δt = b - a and hence b = Δt.

>>10352809
are you in the sun or what?

>>10352974
I've been eating on a surplus of 500kcal, sometimes up to ~1000 but I only gain fat. Muscles just won't grow at all, why can't I build muscle? I hate myself

>>10345492
Watch this: https://www.youtube.com/watch?v=kfF40MiS7zA

Let M be an FA with {1, 0} as its set of input symbols, and let w be some string accepted by M. Then:

if δ(q0, 0) is undefined, then w = 1v, for some string v;

Is this true or false?

>>10353988
>false
Because the premise does not allow you to conclude that δ(q0, 1) is not undefined.

>>10352131
Okay, so what you're saying is that some equations are simply used to represent some observations, or that some equations that have actual meaning were manipulated into a prettier form, for the sake of simplicity. I didn't want to mention physics because I feel that all equations either have a concrete meaning, aka you can connect it to the real world, or they were derived and simplified from some more difficult equations, but it's possible to trace them back to their roots to get the concrete mathematical relation that, despite being complicated, has implications in the real world, whereas its simplified derivation is merely a tool.

Also before anyone responds, yes I know that physics is based on real world observations and that we use math to represent what we see, but in case of idk mathematics used to represent some findings/results from some poll asking various random people (old, young, different races of people) whether they preferred bigger or smaller dogs, the math used to represent those findings doesn't really have any deep meaning other than representing the results, which could probably not be repeated to the exact formula had this question been asked elsewhere, in another city, county, country etc.

The point is, math with concrete meaning and math merely representing some findings without any deeper meaning behind them

>>10354109
could it be possible that the empty string would be accepted by M, if q0 is a final state?

When they ask me to find the energy of this, am I supposed to actually find the power?
I thought that energy on signal was only meaningful if it approaches 0 as time goes to infinity.
In this case, it's a sinusoidal function so would I just integrate f(t)^2 between -T/2 and T/2? Also, what happens when you double the signal and multiply by a constant k? Doubling just increases the amplitude and multiplying by a constant increases the amplitude?

>>10346661
I mean if you really want to be obnoxious about it, you could take into account the likelihood that the person rolling can exert some amount of influence over the outcome by using their hands or a wall. Apart from that I can’t see why you’re being told this is incorrect. Did they give you any explanation?

Can someone help me understand electric potential? So let's say we have two metal plates, same amount of charge on both, but one's positive and the other's negative. And let's say that there's a negative point charge in between. So, physics says that the closer the negative charge is to the negative plate, the higher potential it has. So, it's not about the force the charge experiences, because the further away it gets from the negative plate, its push decreases on it, but at the same time it's getting closer to the positive plate and its pull increases reversely proportional to the push of the negative plate, but it comes down to the distance it has to travel between the two plates?

do the japanese use a different math notation?

>>10354141
Yes.

>>10354380
wish I had this kind of math problems in school, would have payed way more attention

How to get into science?
How to stop being an brainlet?

How much do we not know?

>>10354380
exquisite

Is injecting my semen in eggs and animals ethical?

>>10354998
As long as the animals enjoy it.

I'm doing calc 2 atm, what's the best material/book/site/video for this? My professor is good i just want to revise the lecture from something simple at home. I don't want something like Stewarts calculus, i tried that at calc 1, good book for exercises but a shitty one for actually learning.

I'm currently reading spivaks calculus but looks like It's gonna take a long time before i get to the integral chapter ( i started finished the first one today). I just want something before i get to the integrals chapter thx.

>>10343783
What the fuck could I be doing wrong? I have this data set; for each X value there is a Y value. When I divide each X to each Y, I get approximately 'N' (the values don't matter). But when I plot it and draw a best fit line, the slop is no where close N
What the fuck is wrong with me.

>>10354360
Not quite sure what you’re asking here. The electric potential assigns a number to each point in space such that the electric field points in the direction where the numbers decrease the fastest. The force experienced by a particle will be along this direction (or opposite depending on its charge), with a magnitude proportional to how fast it decreases. For two infinite metal plates, the potential varies linearly between the plates. Since the slope of the potential is constant between the plates, the force experienced by a particle is the same at each point.

>>10355270
Are you getting a slope of 1/N? If so, you’ve mixed up the X and Y axes.

>>10355270
>>10355340
Messed up replying.

>>10354948
Read a book
Do exercises
If you want to be scientist
Go to college

>>10355017
nigger

>>10343783
Cute dinosaur! I love conures!

Is it too late at age 23 to go for a masters in financial mathematics? I read 2 years for ChemEng, which I have fallen out of interest in, and 1 year of business which made me fall in love with finance. Math was not my strongest subject but I have a real thirst for it now. Im in Sweden so changing programs isn't as much of a deal as it seems in the US.

>>10354948

>>10355881
>Is it too late at age 23 to go for a masters in financial mathematics
No.

If a liquid is saturated with a particular solute, can another solute be dissolved into it?

e.g. if water is saturated with sugar, can salt be dissolved into the sugar-saturated water solution?

>>10354360
The potential at any point in a field is the total energy (per unit charge) required to move a charge to that point from a point infinitely far away (zero potential).

A negative charge is attracted to the positive plate and repelled from the negative plate. You need to add energy to move it toward the negative plate, or can extract energy by allowing it to move toward the positive plate.

It's common to use gravity as an analogy, as a gravitational field is also a potential field. Height = potential. The higher something is, the greater its potential. You need to add energy to move a mass upwards and can extract energy by allowing it to move downward.

> because the further away it gets from the negative plate, its push decreases on it, but at the same time it's getting closer to the positive plate and its pull increases reversely proportional to the push of the negative plate,
For parallel plates whose dimensions are much larger than the distance between them, the force on a charge at any point between them is approximately constant. For two spheres, where the distance between them is large compared to their radii, the total force would be the sum of two inverse-square-law forces (a strong repulsive force near the negative sphere, a strong attractive force near the positive sphere, and a weaker force in between).

> but it comes down to the distance it has to travel between the two plates?
No, just the voltage. If you move the plates farther apart, the energy required to move from one to the other remains constant. The energy required to move a given distance increases. With the gravity analogy, this corresponds to the slope of a hill getting shallower while its height remains fixed.

Hello frens, I know I'm missing something terribly obvious. Parametric line tangent to circle, find the value of k. Usually I'd find the slope of the radius and then k, unsure here.

>>10356151
A line is tangent to a circle if and only if it only touches it once.

>>10356151
You can just plug in the values of 1,0,-1 and it's obvious none of them can be tangents

>>10356158
>>10356166
Thanks

>>10343783
Suppose I have [math]f[/math] and [math]g[/math] two linear forms on a vector space [math]E[/math], and define the map
[math]\phi : E \to \mathbb{K}[/math]
[math]u, v \mapsto f(u)f(v)[/math]
Why is it symmetric if and only if [math]\ker f = \ker g[/math]?

Is there a name for the phenomenon where a person, typically young, imagines their future self (3-10 years older) and goes like "imagine being that old lol", "i never want to reach that point, i'll kms sooner"? And reasons why they never actually kill themselves

>>10356408
Riesz representation theorem.
More extensively, assume [math] u \in ker f[/math] but [math] u \notin ker g[/math]. Then f(u)g(v)=0, but f(v)g(u)=/=0.
For the other way around, we use this:
Lemma: Any two functionals with the same kernel are scalar multiples of each other.
Proof of lemma: assume the cokernel of a linear functional f has more than one dimension, and thus contains a two-dimensional subspace spanned by a and b. Then [math]0= \lambda f(a) - f(b)= f( \lambda a -b)=0.
From this it follows trivially.

>>10356451
>forgetting to put the second /math afterwards
Fucking hell.
[math]0= \lambda f(a) - f(b)= f( \lambda a -b)=0[/math]

Why do i need to integrate by parts instead of doing this:

[math]\int e^{-2x} = \int e^{-2} \cdot e^{x},~e^{-2}[/math] is constant, gives: [math]e^{-2}\cdot \int e^{x} = e^{-2x}[/math]

>>10356529
Because [math]a^b a^c=a^{b+c} [/math]

>>10356451
Nice, thanks
Is there a proof of that Lemma that doesn't require cokernels? (haven't gotten to them yet)
I don't need the whole proof, just an idea to get me started will do.

>>10356717
Let [math]f: X \rightarrow \mathbb{C} [/math]
[math]coker ~ f= X/ker~f[/math].

I have
[math]\frac{dr}{dt}=\frac{r^{2}\frac{d^{2}\theta}{dt^{2}}}{-r\frac{d\theta}{dt}}[/math]

Is it true that [math]\frac{dr}{dt}=-r\frac{d\theta}{dt}[/math]? I want to say it's not but I'm never really sure with Leibniz notation.

What would be the best country to apply for a scholarship for a PhD in Chemistry or chem-related field? I live in a cucked country that has you in basically a limbo if you have only up to masters, but also have shit all options for PhD for someone over 30 like me

>>10356864
No, you cant just cancel out derivatives like that. Consider a second derivative of 1 then the first derivative would be t, and the quotient would be 1 / t.

Pls help

I have two highly correlated sets, s1, s2, whats the best equation to use to plot out (and possibly predict) what a s1's value would be when I dont know s2 value

Need to integrate over a region given by this ellipse: [math]x^{2}-xy+y^{2}=2[/math], but I'm having trouble finding the bounds of integration, mainly because I havn't worked with ellipses in a while, let alone one described in a nonstandard form. How best to find the bounds?

>>10357617
If you want change of coordinates:
p^2+q^2=1, where
p=(√6/4)(y-x), q=(√2/4)(x+y)
<=>
x=√2q-(√6/3)p, y=√2q+(√6/3)p
Otherwise, just solve for y by quadratic formula:
y=(x±√(8-3x^2))/2
=>
-(2√6)/3 <= x <= (2√6)/3
(x-√(8-3x^2))/2 <= y <= (x+√(8-3x^2))/2

How do I better understand a mahlo cardinal? Would a cardinal k be mahlo if it were the limit of repeatedly finding larger and larger hyperinaccessible cardinals?

>>10357813
better off asking /mg/

>>10357813
>caring about cardinal numbers set trickery

>>10357903
I don't know why but i find it extremely interesting. I'm also a total novice to set theory

What waifu is best ?

>>10358014
>implying I'd cuck myself by telling you
If you just need an image folder, I could use help diffusing this: >>>/jp/20761912
tl;dr artist deleted all his shit, anon saved some of his shit, I've been posting it to spread it a bit, you could help.

>>10343783
Can anybody help me with this calculus of variations problem?
>derive the euler equation and transversality condition, solve
[eqn]\min_{u(x),b}\int_{0}^{b}((u')^2-2u + x)dx,u(0)=1, u(b)=0[/eqn]

>>10358033
>2hu
Nothankyou

>>10357145
bump

>>10357145
Depends. Is there a correlation delay?
If there isn't, the usual.

>>10357145
>>10358088
I'll give a more concrete answer.
Imagine we have a time series T that we only have data of until time i.
Johnathan, the intern, is tasked with the following: he takes the value T attributes to a time n, picks a random value normally distributed around T(n), and gradually builds a new time series T'.
T and T' are very strongly correlated, but T' in absolutely no way helps predict the values of T.

However, assume we have a series T, and another time series S, such that T and S are correlated, but T(n) is more correlated with S(n-1) than with S(n).
Then we can exploit this to predict T's values through the usual.

>>10345907
You’re not wrong

>>10356451
What’s the painting from

>>10355971
Probably, read about the phase rule and 3-components phase diagrams.

Is (dx/dt)^2 the second derivative, or is it the first derivative squared?

>>10358465
It's generally the square of the first derivative.
The second derivative is
[eqn]\frac{d}{dx}\left(\frac{d}{dx}y\right) = \frac{d^2}{dx^2}y = \frac{d^2y}{dx^2}[/eqn]
The notation is rather intuitive once you understand the motivation.

I got a sponsored message on Linkedin from some professor at Unviersity of San Fransisco about their PSM in Biotechnology...I'm just a sophomore in molbio and biotech...Is it even worth following up, even just for like a summer research opportunity?

Please explain squared error to me.

I've seen it used all the time in engineering, but I've never gotten an explanation as to why it's used instead of just taking the difference.

>>10358685

I'm not sure if you mean something specific but you always want to square deviations, else positive and negative deviations might sum to zero, making you think there is no deviation

>>10358685
For an unskewed distribution (where positive and negative errors are equally likely), the mean error will always be zero, regardless of how large or small typical errors are. But the squared error is always positive, and the mean squared error (the variance) provides a measure as to the statistical spread of the error.

>>10358846
why the fuck not just take the absolute value then, why go through the extra work of squaring

>>10358685
Because two errors of 0.5 are miles better than one of 1.

>>10358238
>>>/jp/20761912

given an integral over a region given by [math]z=1-y^{2}[/math] and the planes [math]x=1[/math] and [math]x=-1[/math], are the appropriate bounds of integration: [math]x\in [-1,1] , y\in [-1,1], z\in [0,y^{2}-1] [/math]?

>>10360013
You switched from the upper limit of z from [math]z=1-y^2[/math] to [math]z=y^2-1[/math], why? The former is correct.

How do I tell that the exterior angles of a convex polygon is 360 degrees?

Ill prob be asking a lot geometry related questions

>>10360290
The sum of internal angles is (n-2)180=180n-360. This gives an "average angle" of 180-360/n. Then, by the definiton, the complement of the average angle is 360/n, and the sum is the average times the number, so 360.

A LED RGB bulb emits a certain amount of lumens (that i imagine are given at whatever colour temperature maximizes them, probably white). How can i estimate how many lumens the bulb would emit if i set the colour to, say, pure red or pure green?

>>10360174
Whoops, typo. Thanks.

I need to show that [math]\mathbf{gcd}(a^{2} + b^{2}, a + b) = 1,2[\math]. I have tried expressing a common divisor as a system of equations, but was unsuccessful in reducing it. Any thoughts?

>>10360979
[math]\mathbf{gcd}(a^{2} + b^{2}, a + b) = 1,2[/math]

>>10360992
>the gcd is a rational number
Question makes no sense, please rewrite.

If n is a positive integer, how can I prove that x is always a positive integer in pic related?

>>10360979

Where do I begin in order to show that this inequality holds true for some vector x not all 0?
I understand that the L1 norm of a matrix is just the maximal column norm, but I don't really understand how to show this.

>>10361086
>>10361086
Notice that every number between 2n and n+1 is twice of some number between n and 1.

>>10361087
Much appreciated, but a and b need not be relatively prime. The question is also incorrect as I have noticed. The original question was to find the gcd, and I
thought it was 1 and 2, but now I see that if [math]a=10[/math] and [math]b=15[/math], then [math]\mathbf{gcd}(325, 25)=25[\math]. I will need to do more work on this.
>>10361074
Correct. 1,2 were (guessed) solutions for the gcd, not a rational number.

FUCK PLANE SWEEPS

>>10361100
This is true of literally every standard basis vector.

>>10361118
I don't get it

>>10344642
Some direct sunlight does more to get rid of fungal infections than all the topical ointments and powder.
I spent years with really bad athlete's foot until I realized if I let my tootsies get some fresh air and some sun then thats the opposite of the environment it needs to flourish.
Wash and dry your feet, get a new bath mat, scrub the shit out of your shower, don't wear socks around the house.

>>10343783
OK, I'm still a babby when it comes to proofs and maths, so don't bully me too hard. A friend sent me something to prove, that the sum of three cubes can't equal to [math]9k+4[/math] or [math]9k+5[/math]. In other words:
[math]a^3 + b^3 + c^3[/math] cannot equal [math] 9k+4 or 9k+5[/math]. He also specified that [math]a, b, c[/math] are integers, and that [math]k[/math] is a positive integer. I elected to try a proof by contradiction, by assuming that [math]a^3 + b^3 + c^3 = 9k + 4[/math], :
[math]a^3 + b^3 + c^3 = 9k+4[/math]
[math]\frac{a^3 + b^3 + c^3 - 4}9 =k[/math]
[math]k = \frac{a^3}9 + \frac{b^3}9 + \frac{c^3}9 - \frac{4}9[/math]
Since [math]\frac{4}9[/math] isn't an integer, and [math]k[/math] is defined as an integer, we can conclude that to be a contradiction, right? And since assuming it again with the other equation yields [math]\frac{5}9[/math], that this logic completes the proof?

>>10361677
whoops, cocked up the LaTeX, wish there was in-reply previews, but oh well. I'll provide clarification wherever needed.

Let's say you have a completely mechanical heart. Aside from the chemical and Hormones used to regulate a normal hearts functions, does that actually pulsing/beating action of the heart actually matter in human physiology?

>>10361086
You can prove this very elegantly by seeing that that is just the factorial representation of 2n choose n. Check out Pascal's triangle if you need inspiration for your proof.

I'm terrible at math to the point where I barely know algebra or anything beyond. I really do want to pursue CS as a career field, but feel stuck and confused about where I should start to get myself there. I never cared for math in high school and always got passed (even though I really shouldn't have) despite never showing any sort of understanding for what I was taught. It's not that I was dumb, but more that I blocked it out because I didn't like math from a young age and hated going to school.

>Do you think it's possible to learn everything I need to know by July when I could enroll for university in the middle of the year, or should I give up on that and focus on starting next year?
>Like I said, I basically barely know algebra, so aside from that, what else do I need to learn?
>Aside from Khan Academy, are there any other websites you'd recommend?
>I have literately never studied for anything in life, so how do I even study things?

I am seriously going to put in the effort needed, but just need a little more guidance from you guys.

>>10361677
x^3 = {1, 0, -1} (mod9)
9k+4, 9k+5 = 4 and 5 (mod9) respectively
You cant make 4 or 5 from three choices from {1, 0, -1}

>>10361677
Are you really sure k can't be an integer? I mean a^3/9 + ... may sum to an integer remember that x^3/9 may not necessarily be an integer btw above is my proof

Can someone please tell me how to actually calculate this? So the actual exercise says there are two charges, 5nC and -8nC that are 2m apart, if we want to increase their distance to 6 meters, that is we have to move one of the charges 4 meters away from another, what's the work done on it? I can't seem to fucking get this right for the life of me. What am I doing wrong?

>>10362158
Yes.
Depends on the country. Euclidean geometry, analytic geometry and algebra are musts, tho. Basic calculus and matrix algebra are common.
libgen.io for pirating books and learning from those.
You read the text, write down all definitions and theorems by hand, and do exercises until you feel confident, then move ahead.
Remember to review later.
>>10362562
The thumbnail looks like the sea, nice.

>>10361258
Then you can't say anything other than d divides 2l in my notation, and surely you can find a case where each happens. I assumed you meant gcd(a,b)=1 because as you noticed, otherwise the result was wrong. You can simplify to this case by dividing a and b by their gcd though..

>>10361677
Your logic is so wrong it's almost induced vomit from me. 1=2/2 so 1 can't be an integer right?? 0=pi - pi so surely 0 isn't even rational???

Anyways, the second reply has your answer

so i'm making a simple script on matlab, the idea is to generate X random points in 3D space which have a minimum separation between them.

i've followed different approaches but the problem is that I don't seem to be able to do it accurately

b= 200
k=1;

while k < b
x = 8*rand(1,b);
y = 4*rand(1,b);
z = 4*rand(1,b);
for i = 1 : b
for j = 1 : b
if sqrt((x(i)-x(j)).^2 + (y(i)-y(j)).^2+(z(i)-z(j)).^2)<0.5
k=k;
else
A=[x(1:i);y(1:i);z(1:i)];
k=k+1;
end
end
end
end

scatter3(x',y',z','o')

this one works for small numbers but the moment b acquires a high value, due to the structure of the loop some new points are generated which do not meet the criteria imposed.

can someone give me an idea here?

I started physics this week and our teacher wanted us to start out with this, but I don't really know how to find the x-component and the y-component in this.
Data: [math] F_1 =35 kN[/math] [math] F_2 =30 kN [/math] [math]F_3 =20 kN[/math] [math]θ_1 = 31 °[/math] [math]θ_2 =30 °[/math]

>>10362917
>[math] \theta = 31 [/math]
Tell your teacher to kill himself and claim you refuse to do your homework because this is fucking bullshit.

>>10362917
How old are you?

>>10362937
I might just ask him tomorrow.
To help me that is.

>>10362948
19. I'm done with high school I'm just taking it as a course.

>>10362979
>19. I'm done with high school I'm just taking it as a course.
You're taking a high school course?

Is there a set amount of free electrons available in a circuit, and does that mean that if the voltage increases, the current increases, since the pull of the electrons is larger due to the larger voltage, so we could measure a larger amount of electrons passing through some point in some unit time, larger than it'd be were the voltage lower in that same unit time?

>>10362994
Yes.

>>10363009
Why?

>>10362937
oh no 31 degrees

>>10363065
Not him but why else other than college wants to drain your wallet in any way possible. The easiest way is of course failing a student who is not prepared for the rigor.

>>10363065
I like keeping busy while working. I never had it in High School because it wasn't on my "line" (I guess everyone in the US has it?) and because I'm going to start at an animation school this summer I wanted to take the course now that I have time.

>>10363081
Oh man, is it really that simple a problem?

alright so lets say i have a table with no weight, but i have a downward force (really supposed to represent the center of gravity of an object in actuality) that isn't in the centroid
how would i calculate the normal force on one of the legs? i doubt it would be the same for each leg

Fucking hell I'm losing my head over this, please help me out m8s.
1/6 + (1/6 × 1/6) + (1/6 × 3/36) = 5/24
But, expanding it:
1/6 + 1/36 + 1/72
6/36 + 1/36 + 2/36 = 9/36 = 4
Fucking 4! Bloody hell, what the fuck is my pea brain not noticing?

>>10363264
>1/72=2/36
No.

>>10363264
What the fuck do you want us to do? I'm confused by your request. Can you just post the actual exercise

>>10363273
I'm embarrassed yet delighted. Thanks, have a good one.

>>10363279
It's a probability exercise. I'm watching the prob and combinatorics lesson at khanacademy because my classes on the subject were shit in school and I also had sleep deprivation at the time. Not the coolest thing to do at 22, but it needs to be done.
This exercise was used as an example in a comment and i'm trying to wrap my head around it, which is why I'm verifying the ratios and such.

>>10363238
alright after thinking about this for a few minutes ive come to the conclusion it's just a torque problem in disguise

I'll take the chance to ask something about this very question: why is the chance to getting a sum of 4 on the 2nd and 3rd rolls 3/36? The fellow who posted the comment with this example didn't explain any of that.

How do I raise my intuitivityness

Can EE or anyone explain how jumping a dead battery on a car works?

How do I find impedence of the capacitor with no frequency on the voltage?

>>10363587
well first off you basically are putting them both in parallel (really putting most of the car in parallel since you connect the negative lead to the chassis)
when both are off there isn't really a complete circuit, there's no power going to anything
when you start the working car, the circuit is closed and the other battery charges
you wait like a few minutes so it has enough charge to start, and then you start the car

there's nothing really complicated about it

>>10363728
there's a mistake probably
capacitor acts as an open circuit for dc signals
this is a differentiator circuit, so with 0 change in v, it won't even do anything

even if it were like 5sin(2t), the "steady state" part makes this make no sense, it doesn't approach anything so there is no steady state

if i had to guess the whole point was to trick you and the answer is actually 0+0j

Hi, im entering a compsci degree (inb4 >maths for brainlets) and wanted to know how i can branch out to actually do something usefull with my life !
I dont want to be stuck doing front-end webdevelopment or work in any "IT" related field other then software-development.
I wanted to know how some of you here got started and what suggestions you might have towards entering a real scientific job/field and where i can gain more knowledge about what is happening in the world of science&math

>>10355993
thanks dude

My intuition is that this is true but I'm struggling to formalize why it's true.

I've tried contradiction/contrapositive but we have no results to work with for strict inequalities.

>>10364212
Let [math] f(x) \leq g(x)[/math] for all [math]x \in [a, b][/math]. Prove [math]\int_a ^b f(x) dx \leq \int_a ^b g(x)dx[/math].
Then do a contradiction.
>>10363414
Practice.

>>10364212
If int f - int g = int(f-g) is less than 0, so f-g must be negative on some intervall contained in [a,b], so f(c) is less than g(c) for some c in [a,b].

>>10364267
What if the integrals are equal?

>>10364248
Should have been strict inequalities, my bad.

>>10362917
>>10363095
Do you not know trig? You should learn that first

The problem is -17^2, I answered 289 but apparently that's wrong? How am I supposed to know when to apply this logic in the pic?

>>10364371
-17^2 = -1 * 17^2

(-17)^2 = (-1)^2 * 17^2 = 17^2

Basically, parentheses.

>>10364394
Thanks I'll keep my eyes peeled next time

>>10364401
Yep. Ambiguity is annoying as hell in math, especially online homework tools. If it were me writing that problem I would have written it as
-(17)^2.
The solution even talks about how the negative isn't inside the parentheses, but there are none so that just makes it unnecessarily confusing.

>>10364421
order of operations ambiguity is always the fault of the speaker.

i need help understanding why pi doesnt equal four/ what is a circle. im sure everyone has seen the pi = 4 proof but if we push in the corners of the square an infinite number of times the former square now has an infinite number of points, just like a circle. so this means that a circle is not just an infinite number of points. can someone please help??

>>10364486
This is an acceptable way of approximating the area of a circle, but not the arc length.

>>10364248
proving that with the strict inequalities is essentially where I'm stuck

Would Reif be a good supplemental book for babby's first modern physics class? I feel like a lot of the important results in the thermo part of the course are being just hand waved away.

>>10361533
you arent done canceling. you can cancel the 3, 7, and 5 from the denominator: this allows you to remove the 21 from the numerator and reduce the 25 to 5.

now the denominator is2*4*6*8, which reduces to 3*2^6.

2^6 can be cancled and reduce the 2^9 to 2^3. now you have

(19*23*5*27*29*31*33*2^3)/3

that 3 can be removed from 33 in the numerator. now you're left with a very large number * 2^3. which satisfies your conditions.

>>10364486
>>10364525 offers a good explanation.
if you imagine instead that you are slicing off the corners of the square so that the slice runs tangent to the circle. now the square has become an octagon; if you repeat this process, the perimeter of the polygon will approach pi

>>10362656
nothing?

>>10364486
By the same argument, the length of the diagonal (which is actually √2) would be 2.

A path made from orthogonal lines will always over-estimate the length of the path its following by a factor which depends upon the angle and which doesn't vary with the number of subdivisions.

Lets say that i measure the volume of 10 different solids in two ways:
- measuring them with a ruler and computing the volume with a formula
-submerging them in water and measuring the displacement
So i end up with two sets of 10 values, each one of which has a certain uncertainty that comes from the ruler/measuring cup precision. What would be a statistical test to compare the two sets? And what would be a statistical test to determine the degree of confidence with which i can say that the values from the two sets are equal?

I'm being asked this in an assignement and i have no idea what to use. My situation is more complicated than the example i made, but conceptually it's the same

>>10364486
If you want to measure how long a line is, would you do so by zig zagging across it along the whole length? Couldn't you sort of "stretch out" the zig zag and get something longer than your original line? It may not be obvious, but you can always stretch it out to the same length no matter how small you zig zag, long as you use right angles.
Same applies for the circle.

>>10364357
Yeah, I figured. It threw me off that my teach didn't want us to use matrices, it just seems much easier in this case, but I got it.

The red dot represents a mouse click. If I connect the red dot to the edges of the triangle and then get the angle between those edges, will they add up to 360 degrees? All my googling says 180, but my code is turning 360.

The red dot represents a mouse click. If I connect the red dot to the edges of the purple triangle and then get the angle between those edges, will they add up to 360 degrees? All my googling says 180, but my code is turning out 360.

If g on Earth were to uniformly increase by 0.01 every year (365 days) for the next 100 years, would humanity be able to adapt to the change in gravity or would it be too fast a rate where life could not adapt fast enough?
Lets assume that, for whatever reason, nothing else (plants, animals, buildings, etc.) are affected by this change in gravity, if only for the sake of simplicity of coming to an answer.

>>10343783
babys first binomial.

How do I get the closed form of
sum from k = 0 to m (m choose k)/(n choose k) ?
I rewrite it as (m!(n-k)!)/(n!(m-k)!) but I still don't get it. I guess there is some binomial identity I don't understand.

combinatorics or graph theory first?

How would you solve this equation?
Haven't taken differentials in like 2 years and this popped up in my electromagnetics class.

>>10366979
You stare at it until it clicks.
[math]e^{ \gamma x}[/math]

>>10364212
>>10364248
Here is what I got for a proof.
I'm not sure if the epsilon I described will work the way I think it works but it seems fine, to me.

The only problem I can think of is that we can't assume f or g are continuous, they are only Riemann integrable. But I also can't think of any insane functions that are integrable but also such that we can't find such an epsilon.

>>10367032
You didn't prove there's an epsilon.
Tip: Weierstrass extreme value theorem.

>>10367065
That only works if (f-g) is continuous, which I can't assume.

>>10367079
Lebesgue integrability lemma.

>>10367170
Also not allowed to use theorems that haven't yet been encountered by this point in the textbook.

I only have the definition of the Riemann integral and that continuous/monotone implies R. integrable, sum/difference/scalar multiplication rules, MVT, and the nonstrict inequality version of what I'm trying to prove.

>>10367190
Mean value theorem for integrals.

>>10367248
see
>>10367079
>>10367032

I can't assume f, g, nor (f-g) are continuous

brainlet here, how do i do part c on this problem? hints or anything

if you transesterify a TAG, does glycerol get methylated? obv the FAs do, but glycerol's nae carboxylic acid.

>>10344647
That's not even bad at all, you must write like a woman

Let be [math](l^2, d)[/math], where [math]l^2 = \{x = (x_n)_{n \in \mathbb{n}} | \sum_0^{\infty}x_n^2 < + \infty \}[/math]. And for [math]x, y \in l^2, \quad d( x, y) = \sqrt{\sum_{n=1}^{\infty}(x_n-y_n)^2}[/math].
a) if [math](x^k)_{k \in \mathbb{N}}[/math] is sequence in [math]l^2[/math] and [math] x \in l^2 [/math] such that [math] x = \lim_{k \rightarrow \infty}x^k[/ma th], prove that [math]\lim_{k \rightarrow \infty} x^k_n = x_n[/math] for all [ma th] n \in \mathbb{N} [/math].
b) Show that [math]A=\{x \in l^2 | (\forall n \in \mathbb{N}) |x_n| \leq 1/n \} [/math] is closed in [math]l^2[/math]
c) Show that [math]B=\{x \in l^2 | (\forall n \in \mathbb{N}) |x_n| < 1/n \} [/m ath] is not open in [math]l^2[/math]
Showing a) was not hard, but I don't think I did b) or c) well since I concluded that both [math]A[/math] and [math]B[/math] are closed by same argument.

>>10367478
[math]P(x)=\frac{1}{3} \delta(x) + \frac{5}{12} \delta(x-\frac{2}{5}) + \frac{1}{4} \delta(x-\frac{4}{5})[/math]

>>10367002
How did you make it click?

>>10367935
B is not closed (e.g. the sequence 1/n is a limit point not contained in B). You want to exhibit a limit point of the complement that's not contained in the complement, showing that the complement is not closed (and therefore, B is not open).

>>10351306
Just buy yourself a bunch of aromatase inhibitors

Can anyone help me figure out how to get from line 1 to 2 RHS of this? I can see why the integral goes to infinity for the case of omega=0, and I assume for any other omega, it's not defined, and isn't infinite. But why would that make the integral 0 for any other omega?

>>10366979
It's a linear ODE, with the characteristic equation s^2- γ^2=0 => s=±γ, so the solution has the form a*e^γz+b*e^-γz, with a and b given by initial conditions.

More generally, any linear ODE consists solely of terms of the forms c*t^n*e^kt where the k are the roots of the characteristic equation (these may be complex, in which case they'll arise as conjugate pairs, resulting in sin/cos terms) and n>0 only occurs for repeated roots.

If the sign was swapped, then you'd have s^2+γ^2=0 => s=±γi which would lead to V(z)=a*sin(γ*t)+b*cos(γ*t) (=r*sin(γ*t+φ) where r^2=a^2+b^2, tan(φ)=b/a), i.e. simple harmonic motion.

>>10362585
Thanks! And no, gcd(a, b) don't have to be 1. If it was, I would have arrived at d=2,1 ages ago.

My scientific ability is fine but my number 1 hurdle to getting a job is going to be social skills. I find it so fucking difficult to make conversation with people I don't know and who are higher up than me. How the fuck do I overcome this? I don't know what the fuck to say to them and I'm terrible at ass kissing.

I'm struggling to understand Einstein notation with tensors, particularly indexes raising and lowering.
Can someone offers a retard proof paper/book with examples? I am getting more and more confused.

With a < b, does:
]-inf; b] U [a; +inf[ = R
or
]-inf; b] U [a; +inf[ = R + [a; b]
?

>>10368922
what about it?
[math]t^{\alpha} \ _{\beta} = t^{\alpha \gamma}g_{\gamma \beta}[/math]
it's that easy, noting to it. If you don't know anything about multilinear algebra, don't stress on the technical details. For most physicists it's just a formalism I think.

>>10368331
Integrate the first term with a test function and observe that it behaves just like the delta distribution. the dirac delta isn't a function, so yusing a test function is usually the way to go to understand it's properties. If you want to learn how to treat integrals like that in general, maybe take a look at https://en.wikipedia.org/wiki/Oscillatory_integral (check the first example there).