#help-36
1 messages · Page 187 of 1
mtt
Yes
thats not enough information: other than the differential equation, were you given any other information?
Just recognizing that $T(x)=\frac\pi2\cot \pi x$
MCAntDJC
recognizing is the wrong word if youre given the result
what is the original form for T(x) that you were given
was it only the differential equation, or was it the differential equation and also the series representation?
I was able to derive the differential equation from the series by using PFD (and I started with the series)
On a phone?
thats what phones are for, arent they
so far the responses Ive been getting back dont seem to understand the problem I am asking, regardless of how long you take to craft them
usually when we talk this out, we can answer this question much faster
no need to type latex on a phone, that takes forever
yes or no, are you open to talk?
Not really, because people around me are sleeping 😔
in that case this is going to take forever
is there a reason why theres always a few minutes between responses?
I'm always anxious or nervous, then usually overthink my responses
yea thats what I guessed
theres something I usually think of when in a situation like that
you have to realize youre not like dealing with confidential information or in front of the UN
youre just answering questions, and wrong questions can be independent of bad communication
wrong answers, then, can also be independent of bad communication
I want you to quickly answer this question: where did you get this problem from?
I made it up, was playing around with a series ($S(x)$) and thought to compare its square to its derivative; then I got an equation for it, rewrote in terms of $T$, and solved for $T$.
MCAntDJC
mtt
then from there, everything else was derived, found, rediscovered, etc.
Ill take a shot in the dark and say you care about what couldve been better in us getting to this point?
I got the right result with $S$, but in trying the same with $T$ I got an error...
MCAntDJC
I think it comes from
so do you see any problems in us taking 3 whole hours just to ask where you got the problem from, or?
maybe we can figure out what went wrong and try to improve on it?
It's most likely from the series above: adding the terms in the brackets gives $\frac{x^2}{(x^2-k^2)(x^2-n^2)}$, but you showed that an extra term comes out of decomposing the expression here.
MCAntDJC
really, nothing?
I dont understand that sort of mentality but we can just focus on the problem then
we already showed that the partial fraction decomposition does not work out
I tried to continue going with the approach and eventually got having to show that the thing on the left converges to pi^2/2, regardless of the value of x
needless to say this isnt happening
theres a few more other things we need to be talking about as well
first, there already exists a clean way of finding S(x)
it uses the weierstrass factorization of sin(x), which you can search up
ln both sides, then d/dx both sides
this shows how cot is closely linked to a series like S(x)
and I imagine would be helpful in showing why those pi^2n and cot keep appearing in zeta(2n)
with that, S(x) is already known to be
so if you wanted to find something more convenient, shouldnt you just work with the LHS instead of having to deal with the RHS
I assumed that I didn't know $S(x)$ was related to the cotangent, then showed it did via the differential equation for its relative $T(x)$
MCAntDJC
we dont seem to be on the same wavelength at all here
what am I supposed to even do with a response like that?
I don't know, but I do know about the sine factorization; I just played with $S(x)$ as if I didn't know it.
avoid combining discord and latex formatting like that, they dont mix well
going to ask, unrelated to the problem, are you aware that there is a major communication issue between us that would help things along if we were to fix it?
Yes
in this message, are you aware that it was talking about the communication issue, and not about the problem?
it was a yes or no question
I wanted to look back and have us both figure out how we couldve communicated better, but Im going to take this silence as that youre not ready
there is nothing else for us to really point at right now, the mistake in the PD has been found, and the way forward after squaring T(x) as a series doesnt look promising
at the top here, the paper shows you had some more promise when the series wasnt squared
as soon as we squared it, we had to deal with this
this is my best attempt at simplifying it, as you can see its not ideal
at the very least itll involve things like S(k1^2) and S(k2^2) of some sort
it looks like you wanted to relate S(x) to a differential equation so that you can avoid getting into this? Idk
other than that, theres nothing else to point at, and we are done here
I can calculate series in parentheses, but it won't be pretty
look at what the parentheses is connected to
those are each coefficients
the result youd get would just be a bunch of coefficients attached to the series, which in itself is too different from S(x) to really be of any use
it cant be immediately related to S or T since it appears to use x = k1, and S and T are both undefined for positive integer inputs
what Im thinking is we find a way around directly squaring T(x)
no other ideas though, and I dont see a way to even do that
for quick reference, the closed form for this, cheating with knowing T(x) = a cotangent, is:
Try using $\frac1{k_1^2-k_2^2}=\frac1{2k_1}\left(\frac1{k_1+k_2}+\frac1{k_1-k_2}\right)$, then rewriting the sums as partial harmonic series
MCAntDJC
wasnt that what I got earlier?
(also it took me way too long to realize why T(x) was so important:)
(its not just the cotangent thing, its got a really nice series representation)
oh right, wrong image
it was supposed to include this one
I did try out using the partial fractions again but the harmonic series I got doesnt seem ideal
You should let $n\to\infty$ to make that last sum vanish (it's finite)
MCAntDJC
I thought of the same, but that doesnt work
wait a minute
why didnt I think that would work, that does work
I was thinking since each term wouldve been a coefficient, we would need the initially finite sums at first
no idea what I was doing, but that just abou tsolves this
so much for throwing in the towel, lets finish this
we now have
WE'VE DONE IT
with this, we might not even need to know what zeta(2) is, we could just leave S(0)s everywhere then use the differential equation & the asymptotes of T to show that S(0) has to be -pi^2/6
You got it? Congratulations!
and all it took was looking at the series a second time
and knowing where we were even going
Exactly! I was jubilant when I found out I tease out $\zeta(2)$'s value from all this
MCAntDJC
you already found it some other way?
even looking at this section of the work, its wild we can find S(0) this way
For me, $\zeta(2)$ appeared as an unknown parameter: I had $T$'s form down to $A\cot(\sqrt{6\zeta(2)}x)$ (I don't remember $A$'s value, but it doesn't matter here)
MCAntDJC
interesting, we have to had taken extremely similar paths to look for asymptotes this way
if you already had T's form down like though in advance, you couldve used it
well I got something completely off at first
Ill have to clean up the work and try this again
in particular, dont group things up as T(x)/x
I had found $T$ by solving its differential equation... and I may have then calculated $T(1/2)$ to get $\zeta(2)$
MCAntDJC
well Ill have to clean up the work I have, but as far as I see it we're done here
We did it—it was fun and enriching for me my first time and I hope you had fun too
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I currently have the 3rd last line as my answer but how did it jump to the 2nd last line??
its a typo
damn!
cambridge has bad worked solutions at times
but what abt the final answer?
how do I get that solution from what I have currently
@grand hound Has your question been resolved?
He factorized and put same denominator
i'm struggling to see the factorising 😭
just remove the (-) from the front of "1"
ok
$-e^{-kx}$ is in common
how should I approach question b?
Alberto Z.
<@&286206848099549185> how to do part b :(((
weird
idk why i see this
dw abt it
With the usual definition of the mean, i.e. the integral of x•p(x) from -∞ to +∞
yeah idk how to antidiff it
i assume I have to use the answer i got in a
but idk how
so can I just switch 1/lambda for k and work with that and also set k=1/lambda on the side
ok yeah I did that and i got it
how about part d?
nvm i got it
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What have you tried ?
Renato
@gentle zephyr Has your question been resolved?
@gentle zephyr Has your question been resolved?

@gentle zephyr Has your question been resolved?
ye, but is hard to explain it in a proof
can you elaborate
yes if and only if n = m
i mean, we can just assume they are not.
and use bijectivity thingy
idk if I am explaining myself correctly @worldly mesa
are you here Squee SQUEE?
no need that
yes, that would be more appropriate
its just that if f(n)=g(n) then g(n)=f(n)
bijectivity helps with the transitivity of the relation
then f(n) = g(n) = 1 = f(m) = g(m)
how would the proof would go like, then?
you want to prove fRg implies gRf
can you give a rough sketch of your idea
if fRg then for some n f(n)=g(n)=1
so we can prove that is symmetric
to show gRf we need to show there is some m s.t. g(m)=f(m)=1
choose m=n and we are done
.
I just noticed it was a, there exists, if it would had been a forall, it would be different I guess
you know what I mean?
I mean, there is no need to use bijectivity here is what I mean
you understand what I am saying?
yeah its symmetric either way
how to prove it?
. this
we already talked about that
I am
Hmmmm
First, in the line "Suppose gRf iff ...."
You should state instead that you want to prove gRf which means the there exists b.....
You should dicard that iff
I WANT TO ASSUME X R Y AND GET THAT Y R X
because when you say you "assume xRy iff exists ..." you assume the equivalence of those things
ye
so don't assume xRy iff exists a ...
and somehow, conclude that y R x
yeah
any hints?
so we assume xRy
then by definition there is an "a"
to show yRx we need to find some b
choose b=a
good
@worldly mesa
no need to ping
you here?
what does it mean for gRf to hold true?
we cant asume g R f
gRf iff there exists b in {1,...,10} s.t. g(b) = 1 and f(b) = 1
we cant asssume g R f
we don't assume it
my point is that by choosing b=a you proved "there exists b in {1,...,10} s.t. g(b) = 1 and f(b) = 1"
and therefore gRf
hmmm.... you should phrase as, we want to show gRf or equivalently that there is a b s.t. g(b)=1 and f(b)=1
choose b=a and then continue
lets start from scratch
no need to
its just that this first sentence in the second paragraph means something else then what you mean
yes
ok, what about transitive property
is the relation transitive or not
no spoilers
do you want me to tell yes or no?
I know the answer yes
how?
how?
you want help with showing transitivity?
ye
first write what you need to assume
then write what you want to prove
then try to understand what approach you want to take
we want to prove f R h
which means?
a = b = c
is hard
do you have an idea?
there's something you're told about the functions here that you've yet to use
There's no need to constantly ping us (my message was literally just a MINUTE ago)
but you wrote everything you did just to conlcude with the real argument
care to elaborate? i dont think I follow?
You can literally delete these lines and it has the exact same result
now what?
wdym "now what"
What's special about a and b here, like, at all?
We know they're equal, sure
But then why are either of them important here?
how do we conclude
ahem
what?
what?
yeah you wanted a c given the b
Also, he is literally typing at the time you ping him - just don't
wat abt antisym
x R y, y R x <=> x = y
this can't happen when the relation is symmetric unless the relation is the identity
choose different x,y such that xRy

yes
like this?
f = id
but they are differnt
it is transitive
edited
I see
just present this counterexample
how?
Lets take a look at f=id and g(n)=n if n in {1,...,8} and g(9)=10, g(10)=9
then f is not equal to g but fRg and since the relation is symmetric then also gRf
,, \ g : {1, \cdots , 10} \to {1, \cdots, 10} \ g(n) = \begin{cases} n &\text{ if } n \leq 8 \ 10 &\text{ if } n = 9 \ 9 &\text{ if } n = 10 \end{cases} \ f : {1, \cdots , 10} \to {1, \cdots, 10} \ f = \text{id}
you can add more detail if you want
yes
just we usually don't put a \iff there
just a space
just a matter of notation
yeah good
Renato
is the identity function bijective?
ye
I think I follow
we would need to show f and g are bijective, but that is left as an exercise to the reader
ok so you are fine
we need to say 3 distinct elements of the equi cla of id
they must be equivalent under the equivalence rela
here we go again
fRId if f fixes some n
so you can use this g from earlier
and another one using the same idea
f R id <=> E x in {1,..,10} s.t. f(x) = id(x) = x = 1
where
ye
so there are infinitely many funcs that do the trick
bijective funcs
for that equi class
not inifinitely many but. . . like a lot
9! or something
yes
the identity function is part of the equivalence class of id
so thats one
ye
another one is the one we defined earlier
@worldly mesa
you here?
this three funtions are part of the equivalence class of id
now what?
the question was 36 aswell
I think you should do that by yourself
its pretty much the ame
just a different relation
please
try it yourself
its good for practice
I cannot always help you with every questioon
its hard
We've told this to you hundred times, and still it seems you don't understand it... @gentle zephyr
But you haven't even started it
please
My guy
You've just worked through a similar question in excruciatingly more detail than would've otherwise been needed
You should, already, have an idea of how to approach 36
I tried doing the proof that the relation from 36 is reflexive, but idk if its correct, can I get some help?
yeah that's it
g o f = g o f is true because equality is reflexive
ergo, the relation R is reflexive
i tried to prove that the relation from 36) is symmetric, can I get some feedback?
Don't just plonk "I want to show that" in the middle; it breaks the flow of the proof
No, he commented that you check what you want to prove
So that when you do come across it, you can realise when your proof is done
You've already said gRh means g o f = h o f
That means h o f = g o f
.
Which means...?
yeah
Yh but you do this at the START of the proof

"Assume A. We want to prove that B. [PROOF]"
Don't do
"Assume A, i.e. [stuff] [half of a PROOF] We want to prove that B. [the other half of the PROOF]"
This just makes it harder to follow
WHICH MEANS...?
(Like, I'm just parroting what you've said; you literally have one line to finish this)
hRg
There we go
[Okay, I'm not gonna stay here any further; I've got CS work to get done
]
fuck my life
@gentle zephyr its ok to struggle but if you need to be handheld for so many similar problems, there's an issue with your learning method, and you need to fix it before doing anything else
wdym?
am i unclear?
wdym fix?
you need to find the issue with your learning method that makes you repeatedly get stuck on the same type of problem
the problem with proofs is that you dont know if they are correct unless you receive some feedback
is very different to what I have done in preuni, like, finding the area between two functions
if you dont know if your proof is correct, it's most of the times wrong anyway
the issue is not specific to this topic
also, some proofs look convincing but at the same time, are just plain wrong, you know what I mean
ive seen you post many similar questions over the past two years. the way you struggle with them has been the same
you struggle for a long time and learn a little something, but then you seem to lose all that progress when you do a similar problem
Proof assistants 
is not true imo, this has been only recently
or could be true, idk, preuniversity was very different
i remember when you posted the same type of linalg problems for a whole year
you had a pattern of struggle very similar to the one you have now
Like the way you think i think you might be interested to learn some proof assistant like lean, rocq, isabelle etc...
back in preuniversity, everytime i tried a linear algebra problem I knew how to start but just, . . ., didnt managed to finish it entirely, like finish the exercise
now, is different sometimes I dont even know how to start
it was a little bit different, now, even if I finish the proof I dont even know if its true or not
this is what i observed from you every time
you struggle for a long time and learn a little something, but then you seem to lose all that progress when you do a similar problem
this is why i think there's an issue in your general learning method
this is my first few weeks in university, doesnt this happen to everyone? is very different from pre university
i think the issue is related to pattern recognition, applying what you learned from one problem to a similar problem
I mean
I think everyone in my class struggles with this, is just that some people convince themselves their proofs are good, but then when they send me pictures they have mistakes, because they receive no feedback from anyone, u know?
May i ask what are you studying
it's normal to struggle but not for so long in the pattern that i described
as I said, this is the first few weeks of university, I am still learning and adapting my study mechanisms, I am open for feedback on it
i need to you to understand that the issues are not exclusive to university. my observations of you are from both pre uni and uni
the observations point to an issue with general learning method. ill restate:
you struggle for a long time and learn a little something, but then you seem to lose all that progress when you do a similar problem
i think the issue is related to pattern recognition, applying what you learned from one problem to a similar problem
so maybe my feedback is to pay more attention to the "big picture" of how you solve a problem. that way it's easier to apply the same method to a similar problem
isnt that the skill that I am trying to develop in order to pass my exams? the hability to apply what I learnt from one problem to another?
i see you getting caught up in the small details much more often than the big picture. part of ideal learning is having a good balance of attention to both small details and big picture
I would argue that math is more about learning how to solve a problem (problem solving). And not about learning how to solve X, so that you can solve something similar to X.
(Just my opinion tho)
my point is, that hability you are describing, that applying past experiences in order to solve any problem you are thrown at, is easier said than done, is exactly the skill my professor wants me to learn, the issue is that I am a slow learner, but that is alright, no?
back at preuni, I managed to develop that skill by doing gazillion different exercises until something clicked in my head every time I saw a linear algebra problem
ofc it takes time. but i see you going through the same pattern of struggle so many times with very little progress, leading to my feedback on how you can improve your learning method
i have to leave now but i can tell you dont fully agree with my observations. as a first step to improvement i suggest reading your previous conversations with helpers where you spend a long time on a single problem. try to note the commonalities in your behavior and perhaps you'll see what i see
of course it's hard to be objective about yourself, so if you still don't agree with me, i'm sure there are plenty of helpers you can talk to who support my observations
My impression is that a big problem you have is your fear of failing. You don't dare to try a problem on your own without someone explicitly telling you what to do. I think this is very detrimental to learning, because you're not forcing yourself to think. It's like trying to learn how to run but with someone constantly pushing on your back
@gentle zephyr I think if you spend 20-30 minutes on each problem, giving it an real, proper attempt, I think you'll be surprised how much faster you'll learn. The point isn't to solve the exercise on your own, the point is to force your brain to think deeply about the problem
Interestingly, the last time I had renato do most of the problem on his own, he can handle it quickly
@gentle zephyr you should only ask for help once you run out of ideas, a lot of this is essentially ideas that you seem to already know or handle
@gentle zephyr Has your question been resolved?
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hey y'all, need help with this one, not sure why I got it wrong, will post my work
pls @ me when someone pops in because the second problem I also got wrong and I assume it's for whatever the reason i got this one wrong is for
right
you are essentially using the difference of squares formula, so the signs underlined in green are GOOD, but the one with red is NOT GOOD
okay because that was new but that's what my calc 1 teacher did so i was like "I guess we're doin this now"
recall the formula is $(a-b)(a+b) = a^2 - b^2$, where in your case $a = \sqrt{4-v}$ and $b=\sqrt{7}$
maybe I just misunderstood in class
Peter
alr lemme redo the problem
you had the right idea multiplying with the conjugate (the a+b term), but you accidentally changed the sign under the root which needs to stay fixed
right on he changed the sign under the root too
ig maybe he messed up or somethin idk
maybe if you show us the problem and solution we can discuss if that is right or wrong
might have been a mishap, happens
alr so I got a question
how do I remove the (v+3) out of the denominatory then
or do I not
ig I could just not
but he told us not to do that
we need to cancel the v+3 term on top and bottom so that we can calculate the limit
and you remove it exactly the same as you did previously
nevermind I do have to
yep
alr well one sec
ohhh I had made a mistake in my numerator
I see
alr lemme try my answer
well
I get -1/(0)
so that aint good
can you show your solution
they shouldn't be under the same root
denominator should be $\sqrt{4-v} + \sqrt{7}$, again watch the signs as you should have gotten a plus
Peter
well you see that's doggone confusin
no it's not
I'm just stupid
alr thx
average math experience:
first, the exercise mentions that x>1
can you rewrite g(x) knowing that x>1?
instead of writing |x-1| could we write it differently knowing x>1?
well obviously we can since you're asking
im dead
but not sure how 😭
:)
right
if instead of x we put x-1
it'd be x-1
|x-1| = x-1 if x-1>0 and |x-1|=-x+1 if x-1<=0
which is equivalent to
|x-1| = x-1 if x>1 and |x-1|=-x+1 if x<=1
boom
amazing
second question, what did you get for the conjugate of h
it eas given but it would be 1
anyways I got that part right now
the conjugate of h(x) = sqrt(x) - 1 is not just 1
oh mb mb
but anyways I literally just put sqrt(x) - 1
and it took it
like
I put (x-1)/(sqrt(x)-1) for my answer
alright, I'll just provide the steps how we got there
since I multipled top and bottom by (1/(sqrt(x)-1)
$$\frac{h(x)}{g(x)} = \frac{\sqrt{x}-1}{|x-1|} = \frac{\sqrt{x}-1}{x-1} \cdot \frac{\sqrt{x}+1}{\sqrt{x}+1} = \frac{x-1}{(x-1)(\sqrt{x}+1)} = \frac{1}{\sqrt{x} + 1}, \quad \text{when } x > 1$$
Peter
so that's like
not what the book taight us to do
or rather
did for this problem
it started by multiplying numerator and denominator by (1/(sqrt(x) -1))
to get 1 for the numerator
that is also a valid option, but it should be noted that sqrt(x) + 1 ends up being in the denominator
right
wait
one sec
I got lost
too many homework assignments and problem open i swear
it's ok, what's confusing you
user error
aka I'm a dumbass
give me just one hot second
so what problem is this even for
this one
this one
alr
okay that's awesome because it gave me my answer for the third part
which i was going to ask about
but like
okay so starting at 1/(x-1)/(sqrt(x)-1)
how do I get to 1/2
plugging in 1 for x at the end
very quickly, why are we starting with this?
that's what the previous answer to the second part was
mb
missed a division sign
that'll change things
sqrt(x)-1/(x-1)
$$\frac{h(x)}{g(x)} = \frac{1}{\frac{g(x)}{h(x)}}$$
Peter
that's on the left yes
ngl didn't see that until after I typed that out
well, please check out this write-up fully and tell me do you understand everything that happens here
I do, and with that
lemme see what I would do first
alr I figured it out, no need for an explanation
thx
aight should be all for now
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There's a hint that was given
(Deliberately missing (e.g., firing in the air) is also a possible option!)
Do we assume A is completely self-interested?
you can enumerate the possible outcomes out of missing, firing at B and firing at C on A's first shot
ig?
but for this to work, there is one big assumption
The answer to this question really depends on whether B and C play optimally, if they do, you can consider all possibilities of A winning along with the respective probabilities
Ok
we must assume that both B and C are not out for A's head
I'd assume they want to win?
that's a fair assumption, but you should mention that in your solution
Yeah
Add that you assume everyone acts perfectly in their own self interest
But just calculate what the next terms would look like given each outcome
From there
you might begin with enumerating the following possibilities as fox said
So assuming A misses, then B will fire at C because he's a greater threat right?
correct
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Heyo, Im working on an uniqueness proof and just wanted to make sure im doing it correctly and following proper wording and technique. Here is the problem:
https://cdn.discordapp.com/attachments/908076393198419988/1415529062834638878/image.png?ex=68c389ab&is=68c2382b&hm=d3634fd17f489c83c8fcb7357a5f16cbe2dc92cbf3b62e8fb5e5daed2ed65901&
BOSS
Existance:
Uniqueness:
was there a more elegant way to do this?
@frank folio Has your question been resolved?
I dont think that this is cleaner, but you could probably have shown that under addition the Complex form a Group and that 0 is the identity.
I dont think the process deviates a lot anyways
Since all elements from a group have only one inverse -> mostly known as an opposite here
@glossy zephyr eh this class isnt in abstract algebra but I got your approach
other than that is it correct?
yea
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ok so if (this is about quadratic functions pre-calculus 11) - we have vertex (p,q) and i have a question that says: y=9-4x^2, is 9 p or q? i know the other one would be a value of 0 but it's just that this one is formatted a little differently than the usual vertex format y=a(x-p)^2+q
you can plot the graph and find out
Look, this is in the standard form of a quadratic function
y=9-4x^2 is both in standard and vertex form
consider the position of the vertex. You can see from the picture that it is on the y axis, so the x-coordinate must be 0
yes
WHAT ok what if i can't graph it cuz i dont have paper and it takes forever to draw a graph
You were asking this in a discord server so I assumed you had internet
and you could use desmos
well at least now you know that an equation can be in both standard and vertex form, and so in this case you can use either
or use both to check your answer
because it should come out the same both ways, so if it doesn't, then you know you made a mistake somewhere
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so y
which parts have you done?
@subtle folio Has your question been resolved?
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i got -e^(3 - x) - cos(3 - x) + sin(3 - x) + c
why is it positive cos and negative sin
did you factor in that you're integrating sin and cos of 3 - x?
not really
what does that change
i would think it could be integrated like sinx
well. Why did you put a minus in front of the exp term?
y = -e^(3 - x)
dy/dx = e^(3 - x) which is what we have in the integral
ok... and did you find that by chance or...?
Just trying to find your reasoning for that
U sub
so you used u sub to compute integral of e^(3-x)
but you didn't use it for the other terms?
i saw 3-x is the power, so using my knowledge of differentiating e^x, i knew that it would be negative since its a -x
idk what u sub is
these questions are supposed to be reverse chain rule
ah sorry I thought you were the one that said u sub
but so you computed dy/dx for y = -e^(3-x)
why don't you try for the cos and sin terms?
it is wrong.
idk why tho
Are you not applying chain rule?
it's not -cos x you're differentiating
it's -cos(3-x)
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Hey guys, I need some help with this:
Thought I had to do a polynomial division here, is that right? Since the top has x^3 and bottom x^2
I looked up a video on how to do that, and the guy in the video says the result has a form like _x^2 +- ^_x +- something
but I am not sure how that works. mustnt my result start with something like "2x" instead of "2x^2"? Because When I do the multiplication back 2x * x^2 = 2x^3,
but when the first x needs to be x^2 then we'd have 2x^2 * x^2 = 2x^4 which doesnt seem right
show the vid?
@cursive pilot Has your question been resolved?
https://www.youtube.com/watch?v=OdlYNZXjmWA
its in German, but as you can see, before even calculating anything he already had _x^2 _x __
Polynomdivision zum Lösen von Gleichungen.
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will try again in a sec, thank you
he was dividing a 3rd degree polynomial by a 1st degree polynomial
that's why he prepared the quotient to be degree 2
you're dividing degree 3 by degree 2
so your quotient will be linear
yes
this is what I'm getting so far, how to proceed here? I dont get 0 as a result
Or 2x-1+(2x)/(x^2-2x-15), yes
integral of sum is sum of integrals, and the third summand has an obvious partial fraction decomp
does that first part mean I can write the 2x-1 in front of the integral?
fraction decomp I use when the part below the line is a higher degree than the part above it yes
int 2x-1+(2x)/(x^2-2x-15) dx = int 2x-1 dx + int 2x/(x^2-2x-15) dx, yes
aah
then I use pfd on the lower part and proceed from there
I will try, thank you! Now to look up how to do the partial fraction decomposition :p
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How many 5 digits number are there whose sum of digits is 43
think about which digits you can even use
0 to 9?
No
what's the biggest POSSIBLE digit sum for any 5 digit number
45
indeed
whats the biggest possible sum if one of the digits is a 1
(why the question mark?)
anyway, yours (43) is only two below that. so surely you can't really have that many different digit combos.
so can we have the digit 1 anywhere?
I thought something like this
Let number be x1x2x3x4x5
Now x1<9 x2<9, x3<9...
Let 9-x1=t1
9-x2=t2
.....
t1+t2+t3+t4+t5=2
So number of solutions are 6C4
Is this correct?
Yeah
but yes
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!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
so n = p * q and p <= sqrt(n) or <= sqrt(n)
is it possible to write a represenation of a prime number using symbols
like how i did with composite integer = p * q
You can't decompose a prime as a product into smaller numbers
Thats the point of being prime
yeah sorry that was a dumb question
Note that when you wrote n=pq, p and q are not prime necesseraly
Anyway, do you see why at least one of p,q is <= sqrt(n)?
for the 7 * 2 example, yes, but i feel like it wont always hold
If both are bigger then can n=pq?
wdym if both are bigger? like if p and q are larger numbers?
Then at least on of p, q must be smaller or equal then sqrtn
so lets say
p > sqrt(n) and q > sqrt(n)
this would imply that p * q > n, which isnt true. so atleast one of p and q needs to be <= sqrt(n)
Yes
Now that you now that
What can you say?
You want a small prime divisor of n
since n, the sqrt of it will always be larger or equal to a prime number that can n can be divisible by?
Elaborate
composite seem to either be divisible by 2 or 3 which are both prime, the sqrt(n) will always be greater than or equal to 2
... the theorem doesnt hold?
but how do you prove p can be prime for any composite integer n
P can be prime
But that not must happen
It can be composite
If it is composite it is divisable by a smaller prime r
And r <= p <= sqrtn
ok so p or q is also composite, and since its composite it is divisble by a smaller prime r. this means that sqrt(n) is also divisible by a smaller composite int r
what do the | mean
Divides
i have to go to class, i am going to close this channel and then repost later. thank you for the help
.close
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Hi
yes please
lemme send the question
ive been stuck on this for a couple days
@meager hedge whats up bro
Hey ready to try again ?
i was just thinking of @ing you 😂
yes please thanks man
Awesome. Do you have a paper and pen ? It’ll help you organize your thinking
yes i do
i wrote it out
The shape
Great. Now what have you done/understood so far ?
so i figured that each cable doesnt really have a force of 9 pounds, because theyre pulling upwards not diagonally
but i just dont know how to express that
Actually
They pull diagonally
But the upward component is 9 pounds
Each cable pulls in its direction
what i mean is see how all cables are tied up
wait
nevermind
@meager hedge
Yes
can you visualy explain to me the 9 pound being the vertical component and not each cable separately
Now the horizontals cancel out
And the verticals compensate the weight
This is the full written detailed explanation
why?
Newton’s first law read the page and tell me what is not clear
i dont know newtons first law
is that F=ma?
That’s the third. But you can use it too
If the object is at rest, then the forces add up to 0
So since the lamp is at rest, the forces that apply to the lamp add up to 0. So the 3 tensions + weight add up to 0
@meager hedge the way im thinking of is it that each is pulling in the opposite direction
it’s like if you push a box with a certain force forward and i apply the same force backwards
It is true horizontally. That’s why they cancel out. But vertically, they all push up
What are you struggling with in this section ?
right, is that what newtons law says
It is ! You can also apply sum F = ma, in this case a = 0 (no acceleration). So you get the exact same result ! Sum F = 0
and mass here being?
yes
Ok so this part is ok ?
i get the horizontals canceling out I guess
what are we really trying to find from the question
We are trying to find the tension vector, expressed as a function of L
but what does this mean exactly
I feel like you’re struggling to grasp this. Do you wanna hop on a call ? So I can find easier examples and you get how this works ?
okay ill see if i can in a bit thank you
thanks man
@tranquil pine Has your question been resolved?
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I don’t have time to adjust my proof but I’m wondering how to fix it
Also assume that for all a ∈ G ∖ {1}, a ≠ a⁻¹
G would be partitioned into k pairs and not n, by the way.
your proof has the correct general idea -- each element pairs up with its inverse, but with 1 getting paired with itself and |G| even, theres gotta be at least one more that has no pair save itself
Thanks
@valid atlas Has your question been resolved?
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My bad bro i was hella tired , mind if i send you a dm?
No it’s alright
Is this part clear ?
