#help-10
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Closed by @final girder
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And doing one step at a time
Notice how you did one step at a time instead of skipping multiple steps
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there is more hard math to be done
Homebound
so we must get this back into its original form
first
lets get d back into original form
so
wait
step by step
just going backwards
$$ -((x+3)^2 +2) $$
what now
Homebound
Expand and simplify w this
yea
There’s no difference between those 2 expressions
Bruh
Yea I figured
$$-(x+4)^2-5$$
Homebound
Homebound
wait
i dont need the whole think including -5 in brackets right? @teal turret
cause thats only multiplying the (x+c)^2 term
not the -5 constant
It’d have to be +5 if u wanted everything in parenth right
lol
so can i keep -5 out the brackets?
which i am NOT doing
so -8 and -11 is what i got
No
So did u keep the -5 out of the parentheses
Homebound
whats hommebound?
This is the same part u got wrong from the last problem, this step
The distribution of the -
Homebound
Homebound
$$-x^2 -8x - 11$$
Homebound
👎
how
-16 - 5
Ye
yep
2023
I ENDED 2022 DOING A MATHS QUESTION
THIS IS THE YEAR THE PROJECT GOES BAMNG
LETS GOOOOOOOOOOOOO
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nice
😂
@frigid robin Has your question been resolved?
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Bruh
whats your question?
• Show your work, and if possible, explain where you are stuck.```
If you don't have question, then close the channel and open a channel when you actually have a question
Send this man to the dungeon where he will rot for all eternity!!!!
Then close the channel since you're not properly using it
.close
Closed by @fierce lagoon
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how to close?
This has to be the biggest bruh moemnt
How do I close the channel?
It was closed by someone else
Oh ok
If you see this, you are good
But it still has my name next to it
dw it will close
Ok
It takes a few minutes to fully close
oh ok thanks guys
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when f(1/n) = 1 and f(-1/n) = -1 , show that the limit f(x) when x approaches 0 doesnot exist
how do i do that exacly ?
What happens when n -> infinity
it approaches 0
So essentially when you take |n| -> infinity, you get f(0) = 1 and -1
But then
Like
Hell breaks loose then
There is a discontinuity yes
So when you take the limit from both sides
It doesn't match up
I.e. the limit doesn't exist
At x = 0, the point of the discontinuity
Prob to do with squeeze
so let me get this right
Its a known result that if lim_{x \to a} f(x)=L, then lim_{n \to \infty} f(a_n)=L for any sequence a_n that goes to a
So, if we can find two sequences that go to zero along which the function has different limits, that would contradict this result
could u type this one in latex , i donot really umderstand it
Its a known result that if $\lim_{x \to a} f(x)=L$, then $\lim_{n \to \infty} f(a_n)=L$ for any sequence $a_n \to a$
Just take the limit from both sides, of f(x) as x approaches 0, by taking the inner limit as n approaches infinity
Sneaky
A discontinuity is defined as where limits as approached from both sides are unequal
oh okay i understand now thank you very much both of you
@desert finch Has your question been resolved?
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Is the following a correct approach to $(\cosh(x+iy))^i$?
$$\cosh(x+iy) = \cosh x \cos y + i \sinh x \sin y$$\
Thus, in polar form
$$\cosh(x+iy)=\sqrt{\cosh^2 x \cos^2 y + \sinh^2 x \sin^2 y} \ \text{exp}(i\tan^{-1}(\tanh x \tan y)).$$\
So $$\ln(\cosh(x+iy))=\ln(\sqrt{\cosh^2 x \cos^2 y +\ i \sinh^2 x \sin^2 y})+i\tan^{-1}(\tanh x \tan y).$$
Therefore we can use $(\cosh(x+iy))^i=e^{i\ln(cosh(x+iy))}$ and that should be it.
𝙹o
@untold cave Has your question been resolved?
Should be what? What's the question?
The question is about whether the method used has any flaws or not
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is this correct
i changed it to y=mx+b
if it was parralel it will be the same
if perpendicular it will be inversed
its none
thanks
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I’m kinda stumped with the following proof. I understand the idea and how it works and all, but I just can’t seem to wrap my head around where the (b-a)/3 value came from for epsilon. It just seem extremely random, how could I have come up with it if I had been coming up with the proof myself?
Probably doing the proof backwards
Maybe even starting with just arbitrary delta and seeing which epsilon it guarantees
Weird way they've done it there tbh
The point here is that if they are not the same you want a value of epsilon that would result in a contradiction since you assumed a != b
choosing e = |b - a|/something makes sense
Although, the further proof is weird ngl
Alright thank you guys
they did give a second proof for that one iirc
using the triangle inequality
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I'd like to have a formula for function along a curve "if doable", for example cosine along exponent, where cosine is non deformed in respect to exponent, has same amplitude and period
It would have to be parametric
I can measure length of a function for constant period
this is a differential geometry question as you need to know the curvature of the exponent
and create perpendicular in any point to map points correctly
but here is a little problem
for any x, I can easily map only previous points
at this point, is this still possible to map properly a point for x without iterative methods?
so, make a tangent, then perpendicular and mapping
but that doesn't guarantee a formula in terms f(x)
You almost certainly cannot
Hence why it needs to be parametric
e^x gets more and more vertical
So you want a wavy line going straight up that passes the vertical line test?
like this?
no
Like I drew
here cosine is symmetrical to y=0 axis
I want it to be symmetrical to y = e^x curve
your only holds for constant period
They want cos along exp
e^t arc length differential is sqrt(1+e^2t) hmm
and slope is e^t
x = t + cos(t)sin(arctan(e^t))
y = e^t + cos(t)cos(arctan(e^t))
this won't be good but maybe it's failures can be improved
length function is taking much time to compute
Don't know how useful it is, but the function's average along exp will equal exp
length function?
For your solution I assume
Do you think t = ln(tan(u)) is too optimistic lol
if it is try integral calculator .com maybe
monikanicity
Desmos doesn't recognize the prime symbol
it does, look for tangent a normal with a for slider
no
oh ok
yeah but
Could you share a code please?
i mean you could technically wrap any graph around it
at least itll look kinda less vertical near the origin
Make one that says 2023
wave that wavy wave with more waves
Make an anime girl next
this one is static to just e^x
I'll try to generalize
yeah
Particularly computers are bad with double integrals lol
Which, nesting the function twice you were somehow doing I think
idk
welp, I got also this from some time ago, it doesn't hold constant amplitude but it works fast
nontheless I couldn't reverse engineer this to find out why it doesn't work for linears (y=x) and fix amplitude
Nah u need to get rid of the f(t) in the g(t) expression lol
Idk maybe not
That screws with the period ig


i have an idea
circular function and fourier series for "one to rule them all" ?
meh, just add step by step
can't wait to
I pasted reworked formula
this is crrect
here

oh
almost
e^(1/10) lmao
this already calculates the required graph in general
your period is not constant
oh
I denoted fe as function along which curve is drawn
fc drawn curve
fl length of fe
call me dumb but where do I enter 2nd function?
what second function
.close?

Bookmark this to the server
nah someone needs to @everyone for this
welp, thanks to everyone invested, happy new year
How long do desmos links last for
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252 million years
forever
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how do i solve this: 2cos(x)+2cos(2x)=0
Use double angle identity for cosine (preferably the one where sine is absent)
👍 thx
@rapid cove Has your question been resolved?
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what are the steps to graphing this?
_____
@timid silo Has your question been resolved?
What happens when you plug in +-2 for x?
<@&286206848099549185>
do you know how to graph sec(x)
I know how it looks
@timid silo Has your question been resolved?
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Hi can someone help me with b5
what about it are you having trouble with?
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hi i need help
lol isn't that the same question which you asked earlier
where you get
yes it is
Ask the doubt directly
$(z-7)+xy(z-7)$
Rock Man
Rock Man
@dim bobcat this step i didnt understood
You know about this property that ab+ac = a(b+c)?
Dosen't matter
i dont know about the formulas
uh?
(z-7) is acting like a there
oh
Common in both terms
Shouldnt it be +xy?
Ah ok
ok
ab+ ad can be written as a(b+d)
Just like it
z-7+7xy-xyz
=(z-7)-xy(z-7)
=(z-7)(1-xy)
okay so in this solution where i have doubt is
as you wrote z-7-xy(z-7)
i didnt understood how did you write xy(z-7)=1-xy
how this?
@dim bobcat
I took (z-7) common just like i took a common in above one
I didn't write 1-xy in place of xy(z-7)
We don't solve anything
to get answer as (1-xy)
We take common
Because we have to factorise
There's no equation here that we have to solve
You agree that ab+ ad= a(b+d)?
i dont even know bcuz we just started the chapter like 2 days back
!
?
Ok
ab+ad= a(b+d)
This is called distributive property of addition
Which is used above
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.reopen
✅
lol
i need it for sometime
What else do you have to ask bro
if i may get another doubt
i may get bcuz i am currently solving
yeah my mom explained it to me
What mistake were you making earlier
not knowing how to solve
@hexed stirrup Has your question been resolved?
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31/pi is the final answer, can someone help
@wild orbit Has your question been resolved?
,rccw
Its a spherical integral
eh
idk but
i guess the integral is not dependent on theta so we can just treat it as a constant 2 pi outside
we can split the integral into 2 bits but idk how to do the um
cos 3phi sin phi
probably convert cos 3phi to trig with just phi
then int
@wild orbit Has your question been resolved?
Would u get the answer as 31 pi/6
idk
I dont understsnd this ,can u like wtite it down or smth?
👍
Looka like someone else have to come in , i eill wait for some time...
cos)A+B) = ...
Oh
Hmm,what about integration by parts?
Yea i used symbolab
I shuld be getting 31 pi /6
👍
Have fun
Will wait some time to see if anyone else will try to help ,otherwise will close the channel ig
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I have done letter b, can anyone check my proof? Btw, it should be a+c/b+d, there's an error
@cobalt kiln Has your question been resolved?
@cobalt kiln Has your question been resolved?
@cobalt kiln how did you justify that a/b < c/d?? Your proof is okay apart from this. Check for the case that c/d < a/b
show that for both of these inequalities a + c/ b + d is between a/b and c/d
@icy badge You don't need to justify it, you begin with it as your definition/assumption. And yes, I was thinking the same thing about whether I should do c/d < a/b to show that it goes both ways. Did you see the second part of my paper?
I think I will say as a note that if you do c/d < a/b, you end up with a+c/b+d also between them, With the same exact procedure as the first one
then, great. Make sure you state that you assume that a/b < c/d not just "such that" it sounds like you are changing the problem
Oh ok, yes. English is not my first language and I don't usually write proofs, so this is really my first time doing this. What about the second part, is it any good? Thanks
looks good to me, great job
ok thanks, btw wait a minute just going to check something
what kind of proof did you do?
you should know
like a direct proof? contradiction? contrapositive?
This is contradiction here
im testing u
very nice
that's fine
Meaning, I don't know all other proof techniques
Btw, I did c/d < a/b and it also works. Although, if you establish that a/b < c/d is set in, do you really need to put the inverse? I mean, this would be changing the number line to something else, even though it also works. I think one would suffice no?
yes, that suffices. Just say that by symmetry, the case or the assumption that c/d < a/b leads the same result regardless
you have to cover all cases.
you covered the a/b < c/d case, but what a bout the c/d < a/b case?
just say it checks out using same argument but different variable names
Yes, I guess I lose nothing doing such a thing also
Btw, I did letter c, do you want to check it?
no thanks
Ok, thanks again for the help btw
@cobalt kiln Has your question been resolved?
The minus one is done at the end, I gave -1 also
The -(ad-bc) part
Nah that's not how it goes
ad-bc=+-1
It could be either
Neither should be disregarded
wait im not following you
It's possible that ad-bc=-1
ok, so writing +- instead should do the trick then right
The minus is already given in the second part, so I only have to write the + to take into account this also
oh i understand now why you inverted the signs
it's because - * +1 and -1 * -1, which gives at the end -+1
@dark stirrup Is that right?
Yes exactly
@cobalt kiln Has your question been resolved?
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\begin{align}
&\text{Prove that,}
&\frac{(x^2+1)(y^2+1)(z^2+1)}{xyz} \geq 8\
&\end{align}
Mushfiqur
For any positive real numbers
Gijs
Proof first that ((x²+1)/x) >= 2
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mediant, not median
"first" mediant implies multiple. I'd write "given mediant" instead.
What I meant by "first mediant" was the one which you obtain by doing a+c/b+d, because you can still subvide your line into other mediants
Yeah I know what you meant
But saying "first mediant" implies that a/b and c/d have multiple mediants
It's just a clarity thing
What word is this
its numerator is
what about here?
wait a minute let me think about this
yes so, as far as I remember, since this is a distance, which is located between a/b and c/d, you know it is going to have some quantity, right?
If it was zero, this means it would be equal to a/b or c/d
when we assume e/f is between those two fractions
It's weak wording, mathematically, but it makes sense.
yes
How would you write it in words?
Something like this
yes ok
I should have specified e/f > a/b and e/f<c/d
and done that it stays superior to 0 in mathematical terms
Your proof is correct up to this point
This indeed is a true statement
But it does not mean that f has no upper bound
Showing what the lower bound is does not mean that it has no upper bound
oh ok, thanks for mentioning this. To be honest, I did consider this case but I was not sure how to interpret my result. I assumed my original statement "disappeared"
btw, just to be clear I'm following, you'Re saying that f < b+d is my upper bound, right?
yes
As a hint
Consider c/d-e/f
You let d1=e/f-a/b
So let d2=c/d-e/f
It must be true that d1+d2=c/d-a/b
Ok, thanks, I'll try to derive the rest of the proof by myself and hopefully my head will "click"
good luck
@cobalt kiln Has your question been resolved?
Ok, so I obtain this final result. I think the first one, -f <=d+b can be disregarded since we are only working with positive values of f here in general, based on what the problem stated
So we only take a look at the second part, with the positive values, and we obtain a contradiction
@dark stirrup is my reasoning correct?
@cobalt kiln Has your question been resolved?
So, I was right to exclude the first one based on what I said?
yes
Thanks again
man, what a problem this was
Take into account it is my first time doing this
You can generalize to consider negative fractions, but it's just the same result with extra work
Yeah it was a non-trivial problem
While I'm happy I solved it, I'm kinda realizing that this pushed and showed the extent on my knowledge
So I'm not sure of how to feel about this, besides that I need to work on myself
Btw, like I already told you, I did not check the paper which I sent you guys after the first time
So everything depended on what my head gave me and what i remembered
And yes, I inspired myself from it, but this is not a problem as long as I don't look at it while doing the problem and I furnish the detials of my steps, right?
The reasoning
self-learning is a self-discipline
This is a hard problem algebra wise
doable, but hard
At the same time, I feel like I have grown from this and learned a lot, just from one problem. Btw, do you still want to see my final paper for letter c or you trust that I shall write a good thing?
ok thanks again. Btw out of curiosity, do you study math at uni?
undergraduate you mean?
I always wondered something when stuyding math at school
since you have to take a number of classes, and you end up piling stuff, how do you manage to find all these tricks in such a short amount of time?
How did you "survive"
like, one week you have to solve some problems, and obviously next week you also shall have to do so
experience
Do you really manage to find the tricks or you jsut have to take some hits sometimes?
"doing" is the best teacher
yes, but you have 1 week for example to solve x problem, with the other classes
I mean, there are no set "rules" to solving problem
But, there are patterns that can be learned
How well you learn them really depends on the person
Some people have a talent
Some don't
If you're doing it in your free time, you have the capacity to develop it
So you indeed have to learn some patterns to make this an effective thing
Yes
And the more you do, the more patterns you learn
It'll help your problem solving
yes, thanks. At the same time, the cosntant time pressure is really an unpleasent thing
I'm "scared" that this will kill my joy
what did you mean here?
If you're learning math on your own, you should be able to develop a talent for it since you seem to enjoy it enough
ah yes, I get your point. Even someone who has a thing for something has to work to become better
nothing comes for free
It was really pleasant talking with you, and you were right to stand on your position in the face of adversity. This is my original error when doing this problem : I considered the upper-bound option, but since I wanted to really solve this problem, I let my bias disregard this option
I was self-deceiving myself
I'm really happy you still did not go with the flow, since this would have put me in the error. Truth is better
Thanks again and good night!
good night
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i need help
Hello?
hi
ok so
mnp congruent tus
angle mnp = tus
mnp = 180- (142+24) = 180-166 =14
2x-50 = 14
or 2x = 64
su = np (cpct)
2x-y= 13
64-y = 13
y=51
@median thicket Has your question been resolved?
Archi don’t give out the whole solution
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In this example, we have 2 free variables in the Ax = b. But why x2 and x4?
Thank you
Basically, the variables corresponding to the pivots are what forms the space of solutions rest form the free variables
I am not sure if this is just convention or if there's an actual theory behind this
I don't know why x1 and x3 are pivots too.
If pivot means a diagonal components that contains non-zero values,
In this example, you can add row 1 to row 2, then component(1,1) and component(2,2) will be non-zero pivots.
That means column 1,2 is pivot column
I think by definition pivot means the first non-zero entry in row reduced form
So, the corresponding pivot variables are x1 and x3
I see. That's clear. Thank you @gleaming ridge
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Can someone hint how to start this
In general, if you have a function, how would you try finding its maximum/minimum points?
u can find the minimum point
and solve for x or?
Yes
Okay i'll try that
Im not sure how to solve for x, as i end up with x^3=-250, and i cant change it so that it would =x as i cant have negative square roots
Show your work
You need to find the derivative first
oksy
step 1
i got, f'(x) = 2x-250x^-2
Okay
when i set it equal to zero, i got this
show me
oh
since you cant have negative answer
there are no critical points
that's that
you done
?
Yes
wait
there is A critical point
you can have a critical point where there is an asymtote
since the derivative is undefined at 0
that's your critical point
I tried finding the derivative
can you give me f(x)
But i ended up with f'(x) = 2x-250x^-2
yea
ok
let me graph it
there are 2 critical points
let me solve
ill let you know when i'm done
okay
huh
is it x≥0 or x>0
0>
so x=0 is NOT a critical point
Okay
so the only critical point is x=5sqrt5
no no no
no?
yea yea
so we set 2x-250/x equal to zero
let's divide by two
so we get x-125/x = 0
add 125/x on both sides
x=125/x
multiply by x
x^2=125
take the square root
x= √125 or -√125
we exclude -√125 because it's less than 0
we can simplify x=√125 to x= 5√5
that's what you get
But do i leave it at 5root5
yes
Probably
you were getting f'(x)=2x+250/x
which implies f(x)=x^2+250ln(x)
but you said f(x)=x^2-250lnx
so you were differentiating incorrectley
i wasnt sure how to move the x without making it negative, i get it now
you made it much clearer
it was fun helping you
Just one last thing,
The answer scheme says "x=5 minimises the area" im not sure what that means
i think your teacher is referencing the area under the curve
can you show me the question
no. 12
ok let me see
i got confused
nvm sry
let me take a look of this
take the derivative
set it to zero
A'=2x-250/x^2
set it to 0
2x-250/x^2 = 0
divide by two
x-250/x^2=0
x=250/x^2
x^3=250
x=cbrt(250)
simplify the cube root to get x=5cbrt(2)
no i made a mistake
when you divide by two you get x-125/x^2 = 0
let me restart
A=x^2 + 250/x
A'=2x - 250/x^2
set it to zero
2x-250/x^2 = 0
divide by 2
x-125/x^2 = 0
add 125/x^2 on both sides
x=125/x^2
multiply by x^2 on both sides
x^3 = 125
take the cube root
you get x=5
because the cube root of 125 is 5
so that's the answer
x=5
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The result is supposed to be infinite but I get 0 instead
And I have no idea where the error is
i found the mistake
The limit doesn't even exist
-sqrt3 times sqrt 3 is not -9
and then if you put 2 in the variable x you get a 0 in the denominator
OH
but then what about the numerator?
It still becomes 0/0
yeah it means you the answer to the limit is still hidden in this formula
It’s because I am supposed to find the point of discontinuity
I should have a number that is not 0 in the numerator so that lim n/0 = infinite
But I already rationalised and,,,I am not sure how else to rationalize it
limited developments and bam good bye limits
maybe I should have multiplied the numerator and denominator with rad(x-2) instead??
But I still would get 0/0 in the end…
I have no idea on how else to solve it though
The other solution would be to simplify something but
They are radicals
😭
I got a result where numerator is 3 and denominator is 0 then it can be equal to infinity right?
yes and how did you exactly do it?
$\frac{\dv {x} (\sqrt{x-2})}{\dv {x} (\sqrt{x²-1}-\sqrt{3})}$
Arnab Pal
Could simplify that first
i wonder if you could do it in a different way than l'hôpital
Well I don't know about any alternative methods actually
Only this thing popped into my mind
Seeing one hint
like what if l'hôpital doesn't work
in this situation yes
but what if you got a limit where l'hôpital used doesn't work?
Well then there would be so many complications
You could simplify
The expression
Or you could apply some theories of series
Like tylor series
Another great example will be this
$\lim_{x\to \infty}{(1-\frac{a}{n})^n}=e^{an}$
Arnab Pal
Well @young solar I think you should use this
L'hôpital
To get your answer
I can’t
I still didn’t do it in the math program
So I can’t use things my math teacher still has to teach
Well I am 14 not I am learning all of these stuff so I don't know that advance calculus sometimes if you can't use L'hôpital then it would be complicated@cold linden
Ohh 🥲
have you learned this online or?
Online
where is the x term in the limit
n tends to infty
use sequence?
Yupp
Yeah I know :, )
But my math teacher dislikes if we use derivates when
- he still needs to teach us
- these exercises are “””simple””” so they are meant to be solved and used without derivates
A classmate of mine did all the exercises with hopital and the teacher said that those exercises don’t count because they were supposed to be done without derivates😭
so no derivates?
yeah you should avoid l hopital if you are learning to solve questions
Yeah 😢
i don't know how to else solve this
🥲
In the meanwhile can I ask you where did you learn derivates and hopital?
This is the only exercise that I couldn’t do so far
So maybe I should at least solve it like you did and then ask the teacher how else to do it (so that at least I can say I did solve the exercise somehow😭)


