#help-36
1 messages · Page 228 of 1
the first is the indefinite integral, its the anti-derivative. the second is the definite integral, it computes to a number
seems vague
the anti-derivative is the inverse of the derivative, its a function. the definite integral is the area under the curve
$\int{f(x)}dx$ = anti-derivative of f(x), $\int_a^b{f(x)}dx$ = definite integral of f(x) from a to b
i mean the derivative represents a tangent line
the integral represents the area under the curve
c2b7
if its indefinite it just represents the entire area under the curve at any given point
the "area under the curve" is the one with a and b
yeah, it would be a function
not really, because it depends on where you start for the area under the curve, thats why the indefinite integral has + C
have you learned doing indefinite integral / antiderivative?
The indefinite integral just gives you a function that you use to compute the area
right
yeah, but you need to compute over an interval, not just at a value
I mean you can go from a to a
hm
But yes
I suggest watching a youtube video about this
Its kinda hsrd to explain over text
which would still just be an interval with 0 measure
i guess its not rly something that matters
Visuals help
i dont need to necessarily know this
what have you gone over so far?
so if an integral doesnt have bounds it cant be improper
Do you have like a specific question or just want to know what integrals are in general
yeah, improper is only for definite integrals
bro its fine to ask a general question
i just didnt understand that difference
Indefinite integrals aren’t real
shut up
??
i feel like thats true XD
I was joking lol but you don’t really see those after a point
Between what
Definite and indefinite?
like thats why i was confused i always assumed it was shorthand for an improper integral between -inf to inf
that indefinite was
yeah, its not helpful, so dont say it
you just confuse people
just didnt make sense for them to not have a bound
no, indefinite vs definite are completely different things
they are related by the fundamental theorem of calculus
If they are bounded the reuslt is a number
Of they are unbounded the result is a function
Think of it this way
For now
alr everything else makes sene
ill open something else if i have another question
.close
Closed by @carmine plaza
Use .reopen if this was a mistake.
Right
Just watch a youtube video
If you want
Its easier to understand
Your choice
i understand i mean that wasnt the issue
All right
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
short question for example if im trying to solve
-3 -1/5 am i supposed to multiply or not
$-3-\frac{1}{5}$
ihave<skissue>
this?
yes
i asked chatgpt and it kept going back and fourth not knowing if the right way was to not multiply or to multiply
thats a subtraction, -3 then subtract a fifth
!noai
Please do not trust ChatGPT or similar AI tools for mathematical tasks, as they often generate output which "sounds correct" but has numerous factual or logical errors. Use of these AI tools to answer other people's help questions is strictly against server rules (see #rules).
anyway -3 - 1/5 is quite clearly a subtraction of 1/5 from -3
don't be surprised if math turns out to be 17 years of great pain and suffering.
thx
full question btw
and you have 17 more years of it in store if you don't stop using GPT to do math
ok so you do in fact subtract 1/5 off both sides here and you end up with x/3 = -16/5
ok, so do it with steps.
i am telling you very slightly in advance what will happen
you can check yourself against me -- if you arrive at the same answer as me, it means you made an even number of mistakes
ik i got something wrong
ignore messy drawing i hate mouse
the -3.2 bit is ok
then you divided by 1/3 on the left (also good), but... subtracted 3 on the right?
you were meant to multiply by 3 on both
the golden rule is you do the SAME THING on both sides
i think i subtracted because it was positive and i moved it over so its negative
this is why thinking in terms of "moving" is bad 💔
its just so i can visualize it better
moving over making it negative yk
thats why im crossing out
chatgpt mightve corrupted me
if a fraction has a - in between you can still multiply?
😵💫
actually i get it
i was dividing it not subtracting it so theres no need for it to be negative
smh
@last forum Has your question been resolved?
Closed by @last forum
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Let A be a set containing n elements .A partition of a set is a set of k non-empty subsets such that
$$A = A_1 \cup A_2 \cup A_3 \cup \dots \cup A_i , ( A_i \cap A_j = \o , \forall i,j = 1;2;\dots ;k )$$
For example: $B={a,b}$ has 2 partitions ${{a},{b}}$ and ${{a,b}}$ \
How many partitions of a set with 4 elements $C={a,b,c,d}$ are there?
Fionna The Unemployed
What have you tried
There is a recursion formula for the Bell number. You can use that
Okay so, I was able to do this problem using recurrence but I couldn't find a closed form or at least non-recursively relationship
eh?
Is it like
$A_k = A_{k-1} + \binom{n}{1} A_{k_2} + \dots$
Fionna The Unemployed
The Bell number is the sum of all Stirling numbers of the second kind
You can easily deduce it, by choosing some k elements as the last set, and n-k elements have their own division:
I tried to find closed form of this recurrence closed form
$B_{n+1}=\sum_{k=0}^{n}\binom{n}{k}B_{k}$
Cogwheels of the mind
Yeah
Okay I also have no idea what Stirling numbers are
Sorry, I am going to reformulate the thought again:
S(n,k) counts the number of partitions of n elements into exactly k non-empty subsets.
Dividing the {1,2,…,n+1} is the same as choose n-k elements from {1,2,…,n}, along with n+1 to make a subset, and B_k many ways to divide the remaining of {1,2,…,n}. For k=0,1,…,n
[ rb{ B_n = sum_{k=0}^n S(n,k) }]
クーリー
What I did was, choose an element m from the set A then doing cases work, if m standalone then it has the amount of partitions of a set with 3 elements ways and so on
I did arrived at this formula
So essentially it is dividing it to cases according to where n+1 locates
^
I know
B_1=1, good to go.
I mean, like how Fibonacci numbers also have a closed form
Does bell numebers have one?
I don’t think so
Yeah,
Dobinski
It’s not very practical though
[rb{B_n = frac1e sum_{k=0}^{oo} frac{k^n}{k!} }]
クーリー
It follows from the fact that a Poisson(1) random number of labels produces partitions with expected count exactly equal to the Bell number.
Yes
Okay I'm still a highschooler
The last thing he mentioned probably is. Beyond that no, all elementary
You seem unemployed
You're absolutely right
I knew it
But if you are interested in combinatorics in general you can always read enumerative combinatorics by Stanley. It’s beautiful
I'll give it a try, the exam I'm going to take are full of combinatorics problems
If you have an exam ahead then don’t mind. I meant a hobby kind of thing in free time
the only thing I love is watching cartoon but it's okay I also love to torture myself sometimes
Thanks y'all
.close
Closed by @tiny kraken
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
about multivar differentiation chain rule, does wuu = wxx * (xu)^2 ?
since d^2w/dx^2 needs to * dx twice and / du twice if treating them as numbers on simple arithmetic
Mmmm well,
When in doubt - you can always take derivatives manually!
By the way, what is w a function of?
Is w a function of x, and x depends on u?
lets just say, wu exists, wx exists, and xu exists
This is not correct btw
Yeah I mean like what is w a function of
Like
w = w(x)?
idk
Okay so w is a function of x and t, since its the wave equation.
So here's the deal.
We want to write w, a function of x and t: w(x, t) into w a function of u and v w(u, v), and namely its derivatives as well. (The reason being is because the question wants us to substitute u and v in place of x and t)
What does the multivariable chain rule say about taking the derivative? I.e
If
w = w(x, t)
How do we figure out what dw/du is?
wu = wx * xu
Mmmm unfortunately not :(
The problem is that u depends on both x and t, so this equation is actually missing something.
Good! Because u depends on x and t, you are effectively doing the chain rule for each variable.
then another question, how to expand this concept onto 2nd d?
wxx = wuu . uxx +...
or wxx = wuu . (ux)^2 +... ?
wait
It will get very annoying if you derive the second derivative expression. The reason being is because wx * xu is yet another multivariate function.
wxx = d/dx(wx) where i gotta expand both d/dx and wx?
That means you have to apply the multivariable chain rule to wx * xu and wt * tu separately, which is not as easy algwbraically as it might seem.
Wdym
wx has its own expression, then d/dx becomes d/du . ux + d/dt . tx
wuh
As a hint, the strategy for this question only requires you to find wuu and ||wtt||.
If you can find those two, you can solve the question :)
Well actually
You dont even need to find those two
The question tells you exactly which derivative you need to find.
Sure 👍
Thx
This is not so much a trick question by the way - if you look at the question once more and see what it wants you to find/prove
What derivative do you think you need to compute?
(Anyway take a break if you need it :)
Closed by @spring abyss
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
how do you solve this? I made it into a quadratic equation, solved for a in 2 diff values like a = -3 and a =1 , and I substituted the a values for both the equation, I get 9 and 809/27. however the answer is 71/27 is there anywhere I'm going wrong
do you know the factorization of a^3-b^3?
if yes, you should be able to factorize a^3-1/a^3
not very sure, but like how do you apply it?
3a-3/a=3(a-1/a)
and you solve for a? or do we like directly substitute it in?
i don't understand what you are asking for
The short answer is no, you don't need to solve for a :)
can we not substitute a-1/a into the second equation?
As d1 implicitly mentioned, you are basically just doing some neat substitution tricks.
if you can express a-1/a in terms of a³-1/a³
why not?
so in that case I can take the value to be -4/3 and solve?
value of what?
a-1/a?
yess
Closed by @languid bay
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
how to calculate Z-transform of n/n! ?
i know that Z-ransform of 1/n! is e^{1/z}
what’s another way to write n/n! that looks similar to 1/n!
1/(n-1)!
yep
alright but what now?
let me see…
yea i think it should just shift nicely
.close
Closed by @tranquil charm
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
how to calculate $\mathcal{Z}$-transform of $\ln\left(\frac{z-1}{z}\right)$?
Slowaq
.close
Closed by @tranquil charm
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
I am trying for an optimized Gaussian elimination, should I only stop when var=number and at the end? I have so far implemented ranking where the first variable is, is like var=number and the first variable in the diagonal being the thing to subtract from the next rows enough or should I full sort?
Note this is parallel on the GPU. X E.
I also have implemented the stop. X E.
Is this better with or without sorting the rows?
Should I just continue implementing and see if the not sort can work?
if you don't need to perform an operation, why would you need to
Oh, is it possible to just not even use a maximum?
Yeah, at worst O(n^3), is there something better I should consider?
Just as optimized as I can make it. X E.
Just fastest I can make it with minimum extra storage. X E.
Thanks for talking. X E.
it really depends on the use case. see
https://en.wikipedia.org/wiki/Gaussian_elimination#Computational_efficiency
In mathematics, Gaussian elimination, also known as row reduction, is an algorithm for solving systems of linear equations. It consists of a sequence of row-wise operations performed on the corresponding matrix of coefficients. This method can also be used to compute the rank of a matrix, the determinant of a square matrix, and the inverse of an...
there are highly highly optimized versions of gaussian elimination available
why would you want to code it yourself
nothing you can produce will come close to what others have done
Are they in Slang shaders?
Okay, can you name one to study?
Thanks for talking. X E.
any useful language should have a linear algebra library available
which has gaussian elimination already implemented
rip ruby
Those... open source? How easy are those to glean from?
start with a book specifically about matrix computations. maybe
https://books.google.com/books/about/Matrix_Computations.html?id=X5YfsuCWpxMC
I already have a basic understanding of matrices. X E.
are you telling me there is no linear algebra library/module for ruby?
sciruby used to be good, but it hasn't been updated in 4 years
https://github.com/SciRuby/sciruby.com
Octopress source for sciruby.com. Contribute to SciRuby/sciruby.com development by creating an account on GitHub.
I am finding a lot of CPU gaussian elimination, any GPU?
do you understand anything or relying on google only ?
Come on internet, GPU parallel non-square. X E.
i prompt everything, google is for uncs
they are still stuck on google
o oki
do you not know how to use the internet?
your mom must have installed discord for you
doesn’t seem like you are explaining you are letting them rely on google only
do not claim ticket if you do not know how to solve
ask your mom to explain to you how discord works next
if you can answer questions, do it. no one's stopping you
https://github.com/ShantaoL/PRBP, is this any good?
Maybe not now
I will do that once I arrive home
then stop flooding help channels with useless sentences
I had to stop by and see what you were doing because I don’t think the person understands what google stuff your sending
next are you gonna use ai?
Well, that was the only open source one I found that was good sort of and it is ten years old. X E.
Not me. X E.
<@&268886789983436800>
??
Well, is there another place to look other than GitHub?
google...?
you can for example also find https://docs.nvidia.com/cuda/cusolver/index.html
how about you actually look
but serious question, do you actually need this whole completely optimized shit. or are you just gonna use it to solve 10x10 systems
Yeah, not much. X E.
you need to spend more than 1 minute googling
I spent most of today and also exhausted GitHub. X E.
Codeberg turns up no entries. X E.
Maybe I am just bad at searching?
you need specific search terms
And it can't be like use our algorithm, it must be like look at ours, feel free to copy. X E.
Nothing is in Slang shaders now so if nothing else I will at least translate. X E.
But the no pivot solver gives me hope. X E.
Please keep whatever personal beef you have with another users attempt to help out of the help channels. It's just going to get in the way of folks getting help.
Anyway, back to the original question, do I need sort or just like put the frontmost variable equation up top to zero out the rest?
I would think any extra work will degrade performance. X E.
Should I just try myself and later ask why it does or does not work?
Yes. Or just use an existing library
And answer this first
Sorry, can't use an existing library unless it is already for all the GPU APIs. X E.
Did you not read this at all
Yes, I might do it on 20000 by 20003 matrices. X E.
I did, historically Nvidia is hard to find the actual algorithms from. X E.
I read some. X E.
Do u guys know someone's explaining How to solve a linear programming problem using the graphical method?
Not for here?
Not your channel mate
Isn't that a mathematical server ?
Wdym ?
This help channel is occupied
If you have your own question, make your own help channel
Oh okay I'm sorry
Well, going through the given link, it does not actually have algorithms, just a use our system ad. X E.
If you can find the repo form great. X E.
And something slow is better than nothing, without an example code, it is nothing. X E.
What? Second to last channel down?
Anyway, either provide an example I can copy or answer the pinned question please?
And all numbers are real. X E.
This is also 4d+. X E.
What does finding a no pivot one mean?
Hi, welcome. X E.
What is a pivot in Gaussian elimination?
I know, I should just look it up. X E.
Oh, the top row that is setting others zero is the pivot. X E.
That no pivot is just wrong. X E.
AI says I can, but blah, AI. X E.
I think just place any first place should work, and don't interfere with solutions should work. X E.
I would almost thank people here if this had come from anyone else. X E.
GPU gaussian elimination is scarce. X E.
I am modeling it on the CPU in Rust. X E.
At least on CPU I know like line. X E.
Any other Gaussian elimination tips?
I think this can work. X E.
Okay, I think this goes in stages, like first set ranks and go for maximum, search for singles, if found then substitute, next set matrix with below top one only, a thread per each element subtracting except the first which stays the same and is needed, then check for single variables, then set that to zero unless single, if single found, use it. Could this be more optimized? X E.
After the set up matrix repeats. X E.
Maybe I should have a single vector like thing of found variables and zero out singles. X E.
So rank->move up one->eliminate one->check singles and place in vector->zero out not singles->start. X E.
Rank can be done parallel per equation with end at first, move up one can be done with a single swap single thread, eliminate one big number of threads, check singles per equation, maybe a next step to move that variable to equals side per equation between, then zero it out in the equations, then start. X E.
Is this efficient or trash 🗑️?
Also the startup is like rank, move up one input, set up matrix not including that index, check and substitute in singles, start. X E.
Also, I should probably have like if absolute value less than some epsilon then zero. X E.
Oh, and also, may as well stop the single variable checker at second variable and if one contains zero variables and last element like after equals is not zero then atomically set a variable, then at the end of the iteration a checker moves it to non-volatile memory, every thread checks that before continuing on the GPU. X E.
I could probably have just addition and if integer=0. X E.
Should I just implement and stop bothering you?
Simplicity wins I guess. X E.
I don't need this any more, thanks for trying all. X E.
.close
Closed by @scenic nest
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
So I'm a calc BC student and I have an epsilon-delta proofs test for continuity and limits. I am 67% sure there will be 3 questions (which are proofs) and 40 minutes at most to finish them. I'm okay with solving them but the teacher told us that at least one of the problems will require proving either the squeeze theorem, uniqueness of limits, or the limit law involving the composition of limits. I know how to prove the squeeze theorem but I hae no idea how to do the other 2 (although I guess that the uniqueness one might involve contradiction). Can someone please help me? My test is tomorrow.
Don't know what you mean by "limit law involving composition of limits" but I should be able to help you out with the uniqueness of the limit
Thank you!
Alright, so, as you might've guessed, we'll prove this by contradiction
Okay
So is our objective here to prove that if lim x->a f(x)=L and lim x->a f(x)=M then L=M?
Essentially assuming there exist two distinct limits and showing they'll be the same, the idea is that if the function converges to both limits, then it is within distance epsilon of each limit for distances lesser than certain δs, we'll choose a δ small enough to be within both of these ranges, and since this can be done for any ε>0, both limits will be arbitrarily close to each other
Yup, exactly
Okay. How would I proceed beyond this?
Would I suppose instead that L does not equal M
That's the start, yeah
Then would I use the epsilon-delta definition of limits on each of the functions separately and assign a delta_1 and delta_2?
That'll be needed, thing is, as always happens in analysis, you need to choose some appropriate epsilon
Which is easy knowing the solution, not so much if you don't
So would we work backwords to find epsilon?
I don't think that'll work
Mainly because without some chosen epsilon "you have nothing"
How would I proceed beyond this then?
You can't choose deltas and as such cannot exploit the limit condition
Choosing the epsilon
The idea for this particular choice is that we want something smaller than the distance between the limits
That is, something positive but smaller than |L2-L1|
For convenience, and without loss of generality, assume L2>L1
Yeah, but you need to set a certain one
That is, say ε=something
Epsilon = L2-L1?
That is exactly equal to your distance
What ways do you know to reduce the value of something while keeping it positive?
Triangle inequality?
That's mainly used to set bounds on absolute values, also, an inequality
So won't give you a valid choice of epsilon
L2-L1 is not a fraction though?
Dividing by integers
(L2-L1)/n ≤ (L2-L1), strict for n>1
And that doesn't change the sign
Oh okay. Would I choose some random interger?
In general, when you want to find a positive value lower than another one you're given, dividing by some positive integer should be your go to choice
Yeah, in this case it works out better if you choose it greater than 2
okay
As if you choose (L1-L2)/2, L1+ε and L2-ε will "almost overlap"
Would 3 work?
Picture it as a line segment separating them both, of length |L1-L2|
Thank you
So well, now you have your ε, (L2-L1)/3
Would this epsilon be for both |f(x)-L1| and |f(x)-M|
Yeah, because you're interested on "getting L1 and L2 close", which is why we chose our epsilon based on the distance between them
And you'll need your deltas for this chosen epsilon
Am I allowed to use the epsilon for both of them or do I have to explain/justify this
Nothing wrong with that
The definition states something happens for any choice of epsilon
Okay
So it in particular will work for that choice of epsilon, in both cases
So with that epsilon, what should I do?
Write out the definition for that chosen epsilon, what would we want to do?
|f(x)-L1|<(L2-L1)/3 and |f(x)-M|<(L2-L1)/3
That is part of the definition
|x-a|<delta_1, |x-a|<delta_2
The whole thing is:
∃ (δi) such that |x-a|<δi implies |f(x)-Li|<(L2-L1)/3
How would I relate the epsilon to the delta?
In other words: there exists some interval radius δi, such that if x is in (a-δi,a+δi), then f(x) is in (Li-ε,Li+ε), where ε is (L2-L1) in our particular case
That is, your deltas are the radius of intervals that "force your function inside other intervals", for intervals as small as you'd like
Because that's not what you need to do in this case, that won't help you
We know that within some interval (a-δ1,a+δ1) something happens, and that within some other interval (a-δ2,a+δ2) something happens as well, they're both intervals centered on the same point, so you can verify that one will contain the other
Now, we want what happens in those intervals to happen at the same time, that is, the function to be within ε of both L1 and L2
Okay. Thank you for your help! I have to go eat dinner now so sorry to not be able to finish this. Thank you for helping me start and understand this more
Have a nice day
.close
Closed by @dawn zealot
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
on a function f(x) it's concave up if f''(x) is larger than 0 and cc down if f''(x) is smaller than 0 right? or is there more to this
and the inflection points are when f''(x) changes concavity?
You can consider x^2 to check the signs
if you ever forget which is which
and this is it
Closed by @burnt timber
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
d/dx (sec(2x^2 + 2x))
sec(2x^2 + 2x)*tan(2x^2+2x)
and then, times the derivative of the angle itself... my question is, how many times?
what
If your question comes from the fact of using the derivative of 2x^2 + 2x twice, no
sorry 😔
chain rule states: $\dv x f(g(x)) = f'(g(x)) \cdot g'(x)$
ig that makes sense bc the original angle is 1.
Here g(x) is the whole 2x^2 + 2x
Closed by @next thorn
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Factorise $x^{12}-y^{12}$
!status
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
1
calvin
is it $(x^6 + y^6)(x^6-y^6)$
calvin
u can still go on
im confused tho
why cant we do x^6 + y^6
WIt but
Wait
X^6 wouldnt work
Would it?
Wair nvm
Im stupid
ty
.close
Closed by @sacred night
Use .reopen if this was a mistake.
what are you asking bro
I forgot my exponent laws for a second
yeah you need to go even further
few more steps
use $x^3+y^3 = (x+y)(x^2-xy+y^2)$ and $x^3-y^3 = (x-y)(x^2+xy+y^2)$ to further simplify $x^6-y^6$ and $x^6+y^6$
How
$x^6+y^6 = (x^2)^3 + (y^2)^3$
and $(x^2)^3 + (y^2)^3 = (x^2+y^2)((x^2)^2 - (x^2)(y^2) + (y^2)^2)$ according to that formula
im guessing you are asked to factorize to the maximum possible extent and not just once
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
How to know if you can factor something or not?
Any example?
what Ann said 
they were just doing a problem on quadratics, btw
okay, I just checked your other thread
Looks like you’re trying to factorize polynomials
ye, just notice that
For example can you factor
x^2 + x + 4
$ax^2+bx+c = a(x-x_1)(x-x_2)$
Labyrinth
where x1 and x2 are the roots of x
This always works
However, I'm guessing you're restricted to real numbers, will have to check
I mean if you allow irrational and imaginary roots, any quadratic is factorisable
if you want only real roots, the condition is discriminant >= 0
if you want only rational roots, the condition is discriminant = perfect square
I mean like this
oh, those
basically that's about if you can match it to the given form
say if you have 8z^3 - 125
that's (2z)^3 - 5^3, so you can use the form for a^3 - b^3
perfect squares and cubes
Do the first one please
wdym by do the first one
for any polynomial $ax^2 + bx + c$, consider the discriminant $\Delta = b^2 - 4ac$
1 divided by 0 equals Infinity
if $\Delta \geq 0$, it's factorizable
1 divided by 0 equals Infinity
else, you can't factor it
specifically, if $\Delta = 0$, you can turn your quadratic into a perfect square
1 divided by 0 equals Infinity
@mint mural
I got 3 + sqrt(11) and 3 - sqrt(11)
those are fucking zero points
get their decimal approximation
put a scale on your graph
and put a point around that approximation
Ok @final tangle
@mint mural Has your question been resolved?
what's your original question
!original
Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.
because it seems like im confused of what you are trying to ask
firstly, you asked when is a polynomial factorizable, secondly, you go on with your zero points
what question are you trying to encounter?
.close
Closed by @mint mural
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Hi, is my solution right? Probability item 🥲
Mia draws two pens one after another from a box that contains 5 red pens and 6 blue pens, without putting any pen back. Let X be the random variable that indicates how many blue pens she draws. Determine the possible values of X. Compute the mean of the probability distribution.
your probabilities are wrong
given there are 5 red pens and 6 blue pens, what's the probability Mia draws a red pen?
is it 5/11
yep!
alright, and we take the red pen out, so now there are 4 red pens and 6 blue pens
wait is the first or second table wrong
the 2nd table
so how do i put this down in the table tho..
cuz what i did, i based it off the first table
can you answer this for the 2nd red pen first?
once you get the logic for RR (X = 0) the rest will follow
4/11
but arent we looking for the blue pen tho
it's not 11 anymore!
yep
then simplify
.
I don't know what you mean
Let x be the random variable that indicates how many blue pens she draws.
Determine the possible values of X. Compute the mean of the probability distribution.
yes, so I'm correcting you on 'compute the mean of the probability distribution'
you've done 'determine the possible values of X' correctly
well you just needed to write X = {0, 1, 2} but your table is fine
how do i do the 2nd table tho, sorry i just based it off my teachers lesson
do you agree that P(RR) = 5/11 * 4/10 then?
you need to find P(RR), P(RB), P(BR), P(BB) first
ye
ohh
then separate tables for that in the format of 2nd table?
then yes, P(X = 1) = P(RB) + P(BR)
once you find the correct probabilities, then you can do 0 * ... + 1 * ... + 2 * ...
you can't just assume the probabilities are 1/4, 2/4, 1/4
okii, ill write them down first
Like this?
you don't need to multiply by 2/11 or 3/11 at the end of each one
otherwise, that's correct
What do i place in the blanks if theres 4 outcomes but only 3 values
Do i repeat the 1
as I said before, P(X = 1) = P(RB) + P(BR)
Ohhh
,calc (5/11 * 6/10 + 6/11 * 5/10) + 2 * 6/11 * 5/10
Result:
1.0909090909091
that doesn't matter
there's nothing wrong with decimal answers
Oh yeah
we're just looking for our expected number of blue pens to be between 0 and 2
minor nitpick: is P(X) supposed to be a probability or an expected value?
it actually makes sense that our answer is near 1, actually
if we make it 5 red pens and 5 blue pens
and we do it with replacement
then that's just the setup of a fair coin
indeed, they should write E(X)
So 1.09 is the mean?
right, sorry to interrupt
yes
No prob
not at all, I didn't catch that
wasn't looking carefully enough haha
I get it noww, tyzm for teaching my slow brainer 🥹
no worries!
the 2nd table isnt needed anymore right?
yeah, we fixed everything in the 2nd table
it's not needed
okaayy
@versed dawn Has your question been resolved?
Closed by @versed dawn
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
have you tried sketching the problem?
well, C has to lie on the line in order to divide AB, yes?
so ill just plot it at a random place
and given AB as a line segment and C dividing it in the ratio 1:3, which side do you think would be longer: AC, or BC?
Bc
where's the diagram?
right.
so, you are given that BC:AC = 3:1.
have you learnt about the distance formula?
ye
if you have, you can apply it here.
use the fact that the distance from C to B is 3 times that of A to C
let the coordinates of B be (x, y), then solve for that
or, to simplify, you can solve one component (x or y) at a time
which is easier and less headache to track
ack, might be overcomplicated here
you can use this formula where
B(x2,y2) A(x1,y1)
actually, just do it component-wise. I think it's easier that way
it gives you a point in a ratio
yeah this works
try and use that one and see if that works
nice
thanks im prob gonna need more help in a few mins
@pure cliff Has your question been resolved?
Closed by @pure cliff
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
find all functions that satisfy f(2x) = f(x) for all positive integers, how are you meant to approach this, i found that f(1) = f(2) = ... = f(2^k), and that f(3) = f(2^k 3), therefore f(2k+1) = f(2^k(2k+1))
that feels like either underspecified or a really wide class of functions 
It would probably have to be either a constant or a sinusoidal function since it only means for all positive integers
Closed by @sharp wraith
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
2
Making sure my answer suffices
For how nasty a lot of proofs are this one seems pretty simple
What is "a" for ?
@supple nest Has your question been resolved?
dyadic folding identity
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
,, \sum_{k=1}^\infty \frac{n^2}{n+k}
how to calculate this limit
looks like it diverges for most n
wait idk if what i wrote is correct
its $\lim_{n \to \infty} \sum_{k=1}^n \frac{n}{n^2+k}$
no way i wrote it inverted
@rustic sequoia
Try to write it as a riemann sum
which one
Never mind you can brutally make an asymptotical equivalent of the term inside
cancel n on top and bot
i dont get it
You agree this is the same as : n/n²(1+k/n²)
So this is 1/n(1+k/n²)
Look at k/n² for k in {0,...,n} and n tends to +inf
Think and tell me
its 0
If you know enough complex analysis, the way I would approach it is to use the difference equation $$\psi(x+N+1)-\psi(x) = \sum_{k=0}^{N} \frac{1}{x+k}$$. You can then use the $\psi$ to telescope it down.
JessicaK
i see it now , the limit is 1
So what can you say about each term
huh?
it would just cancel out as n -> infinty
I was thinking of saying that 1/n(1+k/n²) ~ 1/n and so you sum on it and its just (n+1)/n which tends to 1 indeed
.close
Closed by @distant scarab
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Let G be a finite simple group. Let p be a prime dividing |G|. Let H ≤ G be the group generated by all elements of order p. Prove that G = H.
What have you tried?
the only thing I can think of is that I need to prove that H is a normal subgroup of G, other than that Ive got nothing
that's exactly it
oh goddammit
I crossed that out because I didnt do it right
.close nevermind on this question too then
Closed by @whole halo
Use .reopen if this was a mistake.
absolutely bombed the final exam because nothing I could think of seemed to work
I didnt even try and work with the ideas I had
thats 2 out of 3 questions I couldve finished had I stuck with them for longer
spent an entire half of the exam time staring at those 3 questions
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
If A is a group, is (A)^n also a group? What about (Z2)^n?
Group with the group set being Cartesian producted with itself n times
okay
The group operation becomes the original group operation of all individual elements from the sequence
do you think it's a group?
(a1, a2,...an)#(b1,...bn) = (a1b1, ..., anbn)
do you need to prove it?
No, I just want to know if it's true in general or not
Oh
that operation is called direct product of groups
usually you would write it like $$\prod_{i=1}^n A$$
slayla
Closed by @digital wave
Use .reopen if this was a mistake.
no problemo
✅ Original question: #help-36 message
So like
Does it fail for other structures
What about rings ornfields
It feels like I remember it failing somewhere
Can't think of any structure the direct product fails on

Pretty sure it holds for rings as well, and, by extension, fields
One thing, though:
In the case of a field, it not necessarily preserves field structure
But it will preserve the ring one
RxR is not a field
Precisely what I said above
Can I keep the channel open for further questions or make a new channel everytime

Bcz I will have more questions
whatever you want. but you should probably close if you won't have any new questions soon
Closed by @digital wave
Use .reopen if this was a mistake.
why do you cry all the time
it's ok
yes you don't keep integral property with cartesian product of rings
(a,0) * (0,b) = 0
Yeah
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Suppose tan theta=x and theta is in quadrant 2, such that x<0. Determine the exact values of sin theta, cos theta, sec theta, csc theta, and cot theta in terms of x. Review before my final and i got i got sin =-x/root x^2+-1^2 (abbreivated from now on as z). sec= z/-1. cos=-1/z. csc=z/x. cot= -1/x. I used an A.I to fact check and its just confusing me. Since its quadrant 2 x is negative so x/-1 as sin is positive in quadrant 2 and cosine is negative, the A.I is saying cot theta= 1/x but isnt it -1/x?
Closed by @halcyon fog
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
I don’t know the complete solution to the entire question, but can provide you some information regarding certain options
I tried jensen
But,I am confused when the double derivative sign changes in second quadrant
wus tha
Jensen inequality
@heavy sparrow Has your question been resolved?
You are on the right track
cos,sin,tan, one of them is concave finction
And (A+B+C)/3 is constantly π/3
One of them is concave on [0, π] I meant
Do you see which one?
Interesting, Jensen leads you to one correct option, but actually two options are correct
Sum of cos = 1+(radius of inner circle/radius of outer circle) and the last term has a range (0,1/2].
you need to use this to deduce the another correct option. If this requires you to select only one, select the one Jensen leads you. The person gave you this exercise probably didn’t expect you to come up with two.
same
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
do we really need to use MVT?
can't we make |f_n(x)-f_n(x_0)| and |f_m(x)-f_m(x_0)| arbitrary small by uniform continuity, since each f_n is differentiable which implies continuity and [a,b] is compact so it's uniformly continuous
and |f_n(x_0)-f_m(x_0)| arbitrarily small because f_n converges at x_0
f'=g because of another already proved theorem (basically this theorem but f is assumed to converge pointwise)
@spark swan Has your question been resolved?
you can only make |f_n(x) - f_n(x_0)| small if x is close to x_0
Then you shouldn’t consider it alone, but two , m and n together
$(f_{n}(x)-f_{m}(x))-(f_{n}(x_{0})-f_{m}(x_{0}))=\int_{x_{0}}^{x}(f_{n}’(t)-f_{m}’(t))dt$
Just as the hint said
Cogwheels of the mind
|x-x_0|<=b-a and the thing in the integral can be really small
is this about what I said?
right i realised my goof
i don't get how to how the integral can be made small 😭
f_n’ converge uniformly, so f_n’ is Cauchy uniformly
oh yeah
so i just set the integrand to be less than epsilon/(b-a)
thank you @silver dew and @gloomy river
.close
Closed by @spark swan
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
,, \lim_{x \to 0} \left( \frac{2}{\sin(x)^2} - \frac{1}{1-\cos(x)} \right)
Simplify it into 1 eq first, it might help
Sin²x can be 1-cos²x
1-cos²x => (1+cosx)(1-cosx)
Then you should be able to make it into 1 eq then see how to go bout it starting from there
i got $\frac{1-\cos(x)}{\sin(x)}$
,, \left( \frac{2}{\sin(x)^2} - \frac{1}{1-\cos(x)} \right) = \frac{1-2\cos(x) + \cos(x)^2}{(1-\cos(x)) \cdot \sin(x)^2} = \frac{((1-\cos(x))^2}{(1-\cos(x)) \cdot \sin(x)^2}
Great, use lhopital
i am think it must be this
not allowed
so the limit is infinty ?
Hmm the way you simplified it is off
Yes, it was my mistake. It should have been there 1/(1 + cox(x))
how
i mean this isnt the same as the limit that im asking for
its 1-cos(x) in the denominator
sin²x can be 1-cos²x which can be (1+cosx)(1-cosx) then the (1-cosx)s can be cancelled out
Hmm I'm pretty much sure this is under !noans
oh, I've forgot to write "1-", but when you will solve this you will get the same answer because I solved this for 1-cosx in denominator
!noans
The purpose of this server is to help you learn, not to hand out answers. Do not ask someone to give you the answer directly.
thx
.close
Closed by @distant scarab
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
oops sorry i don't knew it ty
.close
Closed by @wraith tide
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
$\lim_{x \to 0} \frac{e^{2x} +5e^x -6}{e^x-1}$
factor
first and foremost
why not substitute y := e^x
it's practically begging to be made
$\lim_{y \to 1} \frac{y^2+5y-6}{y-1}$
Ann
Closed by @distant scarab
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
hiiii could i get some help on this pls
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
tbh idk where to begin
shoudl i attempt proof by induction
pls help me 😭
knief cmon 😭
do you think it’s true?
ok so what’s the issue
how do i prove it
did you use the definitions they gave above?
ngl i didnt
is this the right idea
