#help-36
1 messages · Page 255 of 1
but the range depends on whether the poly is of odd or even degree
i see i see
if the poly is an odd degree poly, then the range is all real y
odd as in example?
if the poly is an even degree poly, then the range is all y greater than or equal to the min point, or less than or equal to the max point
odd as in having a variable term raised to an odd power as the highest exponent in the poly
that's the definition of degree anyway
i see
so x^3 + x + 1 is an odd-degree poly, for example
while x^4 + x^2 + 3 is an even-degree poly
oHH
anything else you'd like to ask?
nps. do close the channel when you're done with .close
.close
Closed by @jagged root
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 i do word problems like this
is $\gamma$ the radius of the sphere?
حسیب ♥
oh that is an r, ok
hm
so, we know that the radius is increasing at a rate of 2 cm/s, and we want to find the rate of change in the volume
when r=7
let's say the radius is $r$ and the volume is $V$, what is the rate of change of $r$? and the rate of change of $V$?
حسیب ♥
this works, yes
now the thing we have to find is $\dv{V}{r}$, so let's find a formula with $V$ and $r$ in it, then differentiate $\dd r$
حسیب ♥
V=4/3 pi r^3?
now differentiate both sides with respect to r
dv/dr=4/3 pi 3r^2
then substitute that back into the chain rule equation here
we get dv/dt=8 pi r^2
?
technically you haven't subbed $r=7$cm in yet, so you have
$$\dv{V}{r} = 4\pi r^2 \dv{r}{t}$$ for any $r$
حسیب ♥
now we js substitue r=7?
yep
we do it where
here or
here
here, you subbed in dr/dt = 2 cm/s, but you didn't sub in r=7cm
so why not sub in all at once?
but then you should have this step in between so it's clearer
so dv/dt=8X22/7*7X7
$\pi$ is not exactly equal to $\frac{22}{7}$, so you can either write
$$\dv{V}{t} \doteq 8 \cdot \frac{22}{7} \cdot 7^2$$
or simply
$$\dv{V}{t} = 8\pi(7^2) = 392\pi$$
حسیب ♥
but r=7 gives a sign to cancel the 7 in 22/7
thats why i thought to use it
interesting way of thinking about it, because yeah teachers do like to make things cancel
but pi isn't 22/7
you should write the "exact answer" (which is 392 pi) and then you can use 22/7 if you don't have a calculator on a test, for example
ok
so here are the general steps:
- write out the chain rule [ dv/dt = (dv/dr)(dr/dt) ]
- write the formula relating your variables
- differentiate to find the unknown derivative (dv/dr in our case)
- sub into the chain rule
- sub the specific time (r=7)
do those steps make sense with what we did?
ok ill try another qs and let u know if i face a problem
yes they do
ok, sounds like a plan :)
one doubt
dx/dx^3
is it 1/3x^2
or 1/3*x^(-2/3)
should be 1/(3x^2), dont forget 
if you're ever confused, sub y=x^3
so that makes it d(y^1/3)/dy
then $\dv{x}{x^3} = \dv{(y^\frac{1}{3})}{y} = \dv{y} y^{\frac 13}$
حسیب ♥
wdym eng is not my first lang 😢
ahh ok
alr
in this qs my solution is
dv/dt = 27
d a^3/dt=(d a^3/da) * (da/dt)
27=3a^2 * da/dt
now a is given as a=4 because v=64
27=3*4^2 da/dt
da/dt=9/16
now we need to find dA/dt where A=area=6a^2
d 6a^2/dt
=6* da^2/da *da/dt
=12a * 9/16
putting a=4 we get dA/dt=27
@grand flare Has your question been resolved?
?
@grand flare Has your question been resolved?
Closed by @grand flare
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.
Can anybody explain how this works
I don't understand why they decided to do U sub
I did it normally and got it right
That's fine. Both options are valid
u subs of the form u = ax + b are pretty trivial
.close
Closed by @plush haven
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.
if im reading this right, i have to prove that
limn->infintity can = ca?
yes
do i have to make note for all the cases ot just prove it?
wdym by "cases"
so, my book says we have to consider 2 cases:
- c = 0
- c is not 0
but, like, do i have have to consider both of em?

If you are done with this channel, please mark your problem as solved by typing .close
|ca_n - ca| < epsilon
|c| |a_n - a| < epsilon
a_n - a < epsilon/c
a_n < epsilon/c + a
is this right?
and then do it again, but at step 2 replace a_n with epsilon/c + a
mhm for the start but don't drop absolute values
!occupied
Someone else is already using this help channel. If you need help with a question, please open your own help channel/thread (see #❓how-to-get-help for instructions).
wdym?
i dont have a why, i just dropped it to move the variables
????
what
$$|c| |a_n-a|<\varepsilon \implies |a_n-a|<\frac{\varepsilon}{c}$$
Civil Service Pigeon
the original limit definition has absolute values anyway
so it's not like you need to have no absolute values in the end
I should also say that you shouldn't start with $|ca_n-ca|<\varepsilon$ since that's assuming what you're trying to prove
Civil Service Pigeon
but when you write it in reverse, it's fine
I thought it was obvious at first, but perhaps it deserves a quick remark
idk
then what do i start with?
with the given condition?
the way i do is:
Let E > 0
then that step
yeah with the given condition, or just in general
my way of doing this is:
Let E > 0
| f(x) - L| < E
then whatever e i end up getting
Let delta/N (dependong on the question) and then resolvoing it, but replacing it
You're given $\lim \limits_{n \to \infty} a_n=a$ to start with that. You want to \textit{end} at $\lim \limits_{n \to \infty} ca_n=ca$.
Civil Service Pigeon
the overall methodology and rules of how to write proofs doesn't change just because what you're writing the proof about changes
im lost on what ur trying to say
You want to prove that
$$\lim_{n \to \infty} a_n=a \implies \lim_{n \to \infty} ca_n=ca.$$
When you prove $A \implies B$, it's common to start with $A$ and do stuff to end up at $B$. (Granted this isn't the only way to do this - contrapositive and other methods exist for example.) What you \textit{should not do} is start at $B$ and end up at $A$ - that would prove $B \implies A$ rather than $A \implies B$. (You may recognise this as proving the \textit{converse} of $A \implies B$ instead.) A common example of why this is an issue is because you can do stuff like
$$1=2 \implies 1 \cdot 0=2 \cdot 0=0=0$$
which allows you to end up with a true statement even if you started with a false one (\textit{vacuous truth}).
Civil Service Pigeon
hes saying to do this in reverse basically
🙂
that is what the question asks
so, what i did is... right? im not going b to a?
reverse how?
you start with $\lim \limits_{n \to \infty} a_n=a$, and you want to show $\lim_{n \to \infty} ca_n=ca$.
you did it the other way around
which is wrong
Lemme try , you assume $\lim_{n \to \infty} a_n =a$ is true. From this you wish to show $\lim_{n \to \infty} ca_n = ca$
how do i bring in C if i start from a_n = a?
if |a_n - a| < epsilon, then |c||a_n - a| < |c| * epsilon right
you are just multiplying both sides of the inequality by a positive number
oh
@ripe crater Has your question been resolved?
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.
DiffEQ,
In the most recent homework two of the problems seemingly don’t appear in my notes really at all. I write everything that I said and done, so I have no idea how to solve these questions. My friends in the class had no idea either
I’ve attached my notes to this message as well
Just a way to get started would probably be ideal, especially using concepts from my notes, but any help is greatly appreciated
You want someone to read your notes to help you get started?
That's the whole point of taking notes
I mean, Ive read my notes, Im not sure what part applies to these questions
I wrote them too ig lmao
good handwriting
haha thanks
What part of the instructions in the question is confusing you
yeah so, neither couchys theorem, superposition principle, or the wronskian really apply to verifying two parameter families of functions of nonhomogenous DEs
Superposition deals with homogenous
Well do you know what the question is asking
How do you make such neat notes and not burnout
Im gonna be honest, not entirely?
Yea do that first before reading your notes
bro it can be tiring, 75 minutes of straight writing, after class im exhausted
ok fair enough
It's just telling you to plug the solution given into the DE and show that it's true
what does two parameter mean in this context?
$c_1$ and $c_2$ are called parameters
riemann
ah ok that makes more sense
Aren't we just supposed to plug in the values?
I guess yeah, we finished first order DEs now were onto higher order DEs
Just plugging it in worked btw
Thanks @vital crag @lilac bison
I didn't do anything lol
you sort of did

oh also the other benefit is that friends depend on me for notes
aight thanks guys
.close
Closed by @halcyon roost
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 not able to understand which arc makes what angle
Shouldn't be angle POR = 200°?
But I know it's wrong
why do you think POR = 200?
nice one, are you trying to find that angle x?
Angle subtended by an arc at the centre of the circle is twice the
Angle subtended by it
Yez
hint: construct a cyclic quadliteratal involving PQR and another arbitrary point on the circumference
At any point of circle
Yea then?,
I just want to know how to figure out that which arc makes/subtends what angle
It's so confusing when reflex angles come
Okay, say you have picked a point S on the circumference, say on the lower half of the circle (for easier visualisation)
what is PSR?
huh
80
right, can you find POR then?
Oh yea
But I wanna know what was my mistake in previous?
What was your previous reasoning
Angle por = 200
Seeing that other angle 100
Don't those two angles got subtended by same arc?
If not pls explain
yeah 160 at the center makes it 10 for x, nice one 0lante
0lante?
it is not applicable when the point on the circumference lies on the arc
Arc that is subtended?
sorry, just arc
So that 100° angle is subtended by which arc?
it is subtended by the "outside" arc
And Angle POR is subtended by inside arc?
they are subtended by different arcs
if you apply the theorem with the lime arc then it tells you reflex POR = 200 so POR = 160
which is another way to arrive at the same conclusion
@fleet briar Has your question been resolved?
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.
Could you solve this problem? They said wrong
A. 4/7
B. 5/7
!noans
The purpose of this server is to help you learn; please don't ask for direct answers. Ask for guidance, explanations, or feedback instead.
First question is wrong because the parts aren't equal
So I need to make equal
There's a big shaded part that looks like $\frac14$
1 divided by 0 equals Infinity
And the remaing part has 3 parts shaded out of 6 equal parts
Note that these 6 parts represent $\frac{3}{4}$
1 divided by 0 equals Infinity
Try again
.close
Don't edit 😭
Closed by @primal lava
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 really get how I’m meant to do this question,
If Z=1+I Is a zero of the polynomial z^3 +az^2 +bz +10 -6i
Needing to find, a and b, where a and b are real
z = 1 + i?
plug z = 1 + i into the polynomial, you will get 0
if thats the case, since its a zero of the polynomial, plugging that in, will result the equation to become zero
from there you have some equating to do
from this you can equate the real and imaginary parts to form a set of equations
That makes so much sense ty
That makes so much sense ty
.close
Closed by @tough pike
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.
just want to double check if im right or not because i got a slightly different answer but also it seems like the people who made the mark scheme are engineers and wrote g = 10
might as well just say e^2 = pi^2 = g = 10 by that point 💀
oh wait
it literally says
to use g = 10 which again feels stupid because this is maths not engineering
mb
.solved
Closed by @steady 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.
Hello, could someone help me to get started on this?
do you know how to draw the right triangle?
oop
riemann
how did you type it that fast? are you goated or smth?
Will the hyp be the square root of 3?
no
Ah I'm getting my triangles confused
the hypotenuse is sqrt(5) yes
Closed by @slow crypt
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.
im so lost, would i not be able to do question 5 like 4?
where am i going wrong
uh why are you using -3 and -1
i dont understand what's happening in the blue and white but the red purple and yellow is correct
do it like question 4
well its to find a point on the graph i could use as a reference
thats how my teacher showed us
what numbers would work
but doesnt it have to be less than -2 for the first one
my teacher did it like this
we care about the behaviour as it approaches -2
so think like -2.000000000000000000000001
why didnt my teacher just sub in 1 for her example, since the limit approaces 1?
good question
no idea 
thats what i woudl have done
plotting it at -1 is like vaguely helpful for drawing its behaviour
but you know how to draw a line lol
thats true
i dont want her to dock marks for doing it another way since shes super strict about that
idk what to do

ok well uh... go ahead and plot those points but theyll not tell you anything useful about its behaviour at -2
i mean those point dont even work after putting it in desmos
what do you mean by "those points dont even work"?
the graph should go through them
also
for thise one
wouldnt i add arrow heads at the ends (where the blue dots are )
since both sides give 0 at -2 it's actually continuous there
@hardy jackal Has your question been resolved?
can someone check these over:
First is good
Second is good. Small note, for continuity it is not sufficient for the right and left side limits to match. Additionally the function value at that point must also equal the limit.
If the left & right side limits match -> limit exists.
If limit exists AND f(a) is equal to the limit at a -> continuity
would this be better: the graph is continuous at x=−2 because the left andd right limit equal 0, and the function value f(−2) is also 0
yes
would everything else be fine?
yes
.close
Closed by @hardy jackal
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 I solve this? Might be a dumbass question but it's late and can't figure it out
Do I substitute
are you supposed to find just 1 solution or all of them?
you could guess a solution by using 1 + 1 = 2
@paper thorn Has your question been resolved?
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.
What did I do wrong?
you didn't mark the angle of elevation correctly
angles of elevation (and depression) are angles made with the horizontal
What do you mean
yes, its how these terms are defined
Ok
But I have one question
My teacher told me to use alternate interior angles to “move” the angle of depression so it is in the triangle but that would make it the same angle as the angle of elevation so how does that work
Because you will usually be given either the height or length
alternate angles, parallel lines
By moving it inside you can use your trig
the above angles of depression and elevation are congruent by that property
(since the horizontals are parallel to each other)
Oh ok I think I understand thank you
@trail shale Has your question been resolved?
Closed by @trail shale
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.
For number 21 can someone tell me if I am missing something. I feel that what I found for c is not right but I can't find any errors
Also for the green right triangle we have phi for one of the angles and then one of the smaller right triangles has alpha as an angle. In this setup alpha can never be greater than phi right?
@left trail Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
✅ Original question: #help-36 message
@left trail Has your question been resolved?
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.
are you supposed to take the derivative?
what does the question say to do
what to do?
arcsin(x) has a direct result
for the next one use the multiplication rule
2/sqrt(1-x^2/16)
i did but i tihnk i did it wrong
can u show what u did?
small error
it should be $-1/2(-x^2/sqrt(16-x^2)+sqrt(16-x^2))$
what is wrong in mine
u did the chain rule wrong
its 1/2(sqrt(16-x^2)) * -2x no?
Hardik
yes but u are diffentiating sqrt(16-x^2) by d(16-x^2)
so it becomes $1/((16-x^2)^(1/2)) multiplied by d(16-x^2)/dx$
omg
i dont know how to use that bot sorry
its okay
u also forgot too diff sqrt 16-x^2
somehow u managed to square it
okay im going to do the whole product rule again and see what i get
ok
ill try out the bot
$d(ab)/d(x) for a,b are functions of x is a'(x)b(x)+b'(x)ax$
bruh
yes
okay
thats correct for the second part
yes
can i simplify more or is that it
if u want u can make a common denominator
that will cancel out the x^2
Closed by @chrome ermine
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... to solve this:
subseqeucne 1: k^2
subsequence 2: k
the limit for subsequence 1 is 1
for sub2 limit is 1/n which translates to 0
now to use the epsilon-delta/n
how would i find epsilon?
ie... off... ah... eee... my bad k^2
unless i misunderstand, they do not converge (which is kinda a good thing)
nono, my bad, i wrote it wrong
no, the 1/n
so if the subsequence 1 i.e 1 if n is a perfect square is k^2
then subsequence 1 i.e 1/n otherwise can be k
or am i missing something?
so you mean the subsequence f(k_1), f(k_2), ... where (k_i) is the sequence of non perfect square integers i guess
you're not really describing the subsequences well but you have the right idea i think
yes yes
i.. sorry, im not good with knowing the exact terminology of writing stuff
it's ok
so what facts about sequences and subsequences and limits are we allowed here? i'm not sure what you are requesting still
now to use the epsilon-delta/n
how would i find epsilon?
like what are you talking about here?
are we allowed standard facts about sequences like... subsequence converges to X implies ambient sequence converges to X, and a sequence has at most 1 limit point
so, basically to prove it doesnt exist we are using the contradiction,
we say
the limit exist and then prove that, when that cant be done we say it doesnt exist
so, to do that, we need some value of epsilon
ok if no standard facts at all and definitions only...
we want to show there is no L for which there is an epsilon such that for all N, there is an n >= N with |f(n) - L| >= epsilon
or if you insist on contradiction, sure we can say an L exists
yeah
so, how do i find the epsilon which i have to use?
but how, how did we come to the conclusion that 1/2 can worl
well there are subsequences converging to 0 and 1. so the limit kinda needs to be one of those (if we just imagine there is a limit for now)
if L = 0, then there are infinitely many n's such that f(n) = 1, so we'll be able to find one such that |f(n) - L| >= 1/2
if L = 1, similar thing
we can find large n such that f(n) is near 0 and hence |f(n) - L| >= 1/2
@ripe crater Has your question been resolved?
Closed by @ripe crater
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.
HALLO
so last month apparently 3b1b posted this puzzle:
consider a ladybug starting at 12 on a clock. At any momment, it travels 1 step clockwise or anti-clockwise with equal probability (of 1/2). Every time it reaches a new number, the number is coloured red. What is the probability that the last number to be coloured is 6?
now i just came across this
and i have an idea
the issue is i am missing something because of which i am not getting the right answer
Consider the following setup:
Let S be a permutation of the set {1,..,12} representing the order in which the numbers are coloured
clearly, the first element is fixed to be 12
meaning 11! elements in our sample space
.close
Closed by @rustic wedge
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.
What Is the Quasi-Fourier Transform?
@twin pivot Has your question been resolved?
no clue
context? where did you see that
q is quick
quickuasi fourier transform
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.
@old quarry Has your question been resolved?
$$1 - 5\cos^2 x = (\sin^2 x + \cos^2 x) - 5\cos^2 x = \sin^2 x - 4\cos^2 x$$
akeanti
looks like if u simplity the numerator like this and separate both fractions u will be left with a simple derivative
Multiply and divide by sin
Then let t = cosx
Tho it might not work
ill get 1/sin^3xcos^2x
and ill have to integrate cosec^5x
which in itself is a kinda long process
$$I = \int \left( \frac{1}{\sin^3 x \cos^2 x} - \frac{4}{\sin^5 x} \right) dx$$
akeanti
yes
what is inside looks simillar to the derivative of $$f(x) = \sin^{-4} x \cos^{-1} x$$
akeanti
i get something very ugly
that is not easy to see at all
oh well
yea but like u just kinda got to there
yea xD
why not bring cos^2x to numerator as sec^2x and let tanx=t
does that not work ?
yes but the problem is power 5
ull have to multiply and divide by cos^5 to get that tan term
and cos^5 bring to the numerator n write as sec^5
which ull have to break as sec^2 sec^2 sec
the sec^2 can be written as 1+tan^2 but what will u do about the sec
nvm this method works brilliantly
that is not a method they just got the answer and differentiated that..
it looks also possible to be solved using t=cosx and then using ostrogradsky integration method to simplify both fractions
what is the ostrogradsky integration method 💀
smt to help with all those fractions
uhh thats a bit too complicated for me
yeah
||thats the answer||
a reasonable approach is to IBP on $\int \frac{\sec^2(x)}{\sin^5(x)} dx - \int \frac{5}{\sin^5(x)} dx$
@old quarry Has your question been resolved?
o but how will that help?
ohh wait
Ohhhhhhhhh
it cancels
thats crazy
thanks bro
.close
Closed by @old quarry
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.
!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
,w x-2y-1=0, y^2=4x
Failed to get a response from Wolfram Alpha.
If the problem persists, please contact support.
the intersections are ugly though
@cedar obsidian
You're better off parameterising the parabola by $(t^2, 2t)$
Civil Service Pigeon
since this allows you to ||do Vieta's on everything instead||
oh that's smart
yes true
like i form the biquadratic equation right?
its given in the solution and i thought that the solution is messy by that algebra
uhm there's no biquadratic involved
I see a quartic, but it's not biquadratic
slip of the tongue?
but this looks mostly like what I intended
t^4 + ... the 4th isn't called biquadratic?
am i forgetting smh
synonyms
meh I'm not in the mood to debate archaic terminology rn
I'll leave y'all to it since my contribution is basically done
the rest is algebra bash as seen above
.close
Closed by @cedar obsidian
Use .reopen if this was a mistake.
✅ Original question: #help-36 message
solution is weird
it directly says that both are diameters of the circle
it means every chord is a diameter to a circle which is not true
No, it means every pair of chords that bisect each other are diameters
ooh shit
@cedar obsidian Has your question been resolved?
Have you tried anything?
||equilateral triangle|| and ||GP Sum||
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.
hello
no ideas coming to my head :((
Hello
This?
Oh this
it's this
Yeah
ABC is a special triangle. What kind?
reasonable reaction
seems isosceles triangle
Don't play any 3D video game 
Right, which sides are equal?
BC & AC
coordinates of H and then determinant formula for area
Idk what the determinant formula is
concurrence point of medians
it divides median in 2:1
on the median or the altitude passing from H
Exactly
So what is the area of AG_1B compared to that of AHB
And then that of AG_2B compared to that of AG_1B...
Can't we just say it's a equilateral triangle so H is also the centroid.... and the area is a^2sqrt{3}/4...
It would be 1/2 * 8 * 4sqrt(3)/3 = 16sqrt(3)/3
yes
its not coming in format on (sqrt3*a^2/)/4
what are you referring to
Area of AHB
Right sure
@cedar obsidian ?
it should be half right?
.
What's the total length of the median when you say the centroid divides it in 2:1?
3
Right, so...
area is 3 times
Of what
the area of AG_1B is 1/3 times compared to that of AHB
right?
Yeah ok, 1/3
mb for that
So can you express the sum now?
[
\frac{16}{\sqrt{3}} + \frac{16}{3\sqrt{3}} + \frac{16}{9\sqrt{3}} + \cdots
]
BlackidoZΣ
We are not including AHB
oh yes sigma notation is for G_I
Yes
[
\frac{16}{3\sqrt{3}} + \frac{16}{9\sqrt{3}} + \frac{16}{27\sqrt{3}} + \cdots + \infty
]
Can you express this using sigma notation?
BlackidoZΣ
yes
Don't write +inf at the end that's nonsense
but at the end we want to find the infinite sum right a(r^n-1)/(r-1)
then why not directly do it
It's an infinite sum, not a sum where the last term is "infinity"
i am facing problem to convert it into sigma notation
i need to practice that again
You divide by 3 each time
That means you multiply by 1/3
What does repeated multiplication look like?
1/3^n
BlackidoZΣ
[
\sum_{n=1}^{\infty} \frac{16}{\sqrt{3}}\left(\frac{1}{3}\right)^n
]
BlackidoZΣ
now?
Now it's a geometric series
infnite gp right

when that question suddenly come in exam
altho at home i couldn't recall that property of median bymself
@cedar obsidian Has your question been resolved?
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.
Channel closed due to the original message being deleted.
If you did not intend to do this, please open a new help channel,
as this action is irreversible, and this channel may abruptly lock.
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.
Channel closed due to the original message being deleted.
If you did not intend to do this, please open a new help channel,
as this action is irreversible, and this channel may abruptly lock.
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 tasked with finding the supremum and infimum of this set
I need hints
this is first analysis course homework at my uni
[] denotes the floor function
trivial inequalities on the floor dont yield anything
useful
{n√2} is dense in [0,1] because √2 is irrational
@karmic glen Has your question been resolved?
nice, this takes care of the supremum
what about the infimum
i think this was one of the first questions i asked in this server
Closed due to timeout
Use .reopen if this was a mistake.
.reopen
✅ Original question: #help-36 message
simulating it numerically for say n = 1 to 1 million and checking the min result is interesting
chances are you'll be able to recognize what the number is, and that gives you something to aim for
you can show that inf ≥ ||1/2✓2|| using the fact that ||2, 3 are not quadratic residues mod 4|| but i'm not sure how you would show this bound is tight
its not:(
actually i think you can get to tightness using the ideas of this proof
The usual idea is to ||take an approximation p/q ≈ sqrt(2) through pell equation, and look at a_q||
@karmic glen Has your question been resolved?
$m = \lfloor n \sqrt{2} \rfloor$
We have $n(n\sqrt{2} - m) = n \frac{2n^2-m^2}{n \sqrt{2} + m}.$
Since $ n\sqrt{2} > m. $ We get $2n^2 - m^2 > 0$. Because m and n are integers this means
$2n^2 - m^2 \geq 1$.
$$a_n = \frac{n(2n^2 - m^2)}{n\sqrt{2} + m} \geq \frac{n \cdot 1}{n\sqrt{2} + m} = \frac{1}{\sqrt{2} + \frac{m}{n}}$$
Since $m = \lfloor n\sqrt{2} \rfloor$, we know that $m < n\sqrt{2}$, which implies $\frac{m}{n} < \sqrt{2}$. Therefore:
$$\frac{1}{\sqrt{2} + \frac{m}{n}} > \frac{1}{\sqrt{2} + \sqrt{2}} = \frac{1}{2\sqrt{2}} = \frac{\sqrt{2}}{4}$$
k
okay I got the bound thank you
okay this seems like the key insight for the infimum thats pretty cool
imma look into this I didnt know you could do this
oh and thank you also
.close
Closed by @karmic glen
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.
Help
,rcw
B isn't the ans
so what have you tried?
Uh so I tried like solving the line and the parabola tgt to get sm rel bw y and m or x and m and finding the triangles area but I'm getting confused in like when I make the quadratic eqn (after solving parabola and the line) what do I do after it
@alpine shadow Has your question been resolved?
if u have a phone, you could send pictures of what uve done
i can help look for errors or give hints
@alpine shadow Has your question been resolved?
bad handwriting
😭
@alpine shadow Has your question been resolved?
m is such that maxima is attained find the value of t for maxima and put it in the eq with m
as F lies on y = mx+c asw
Closed by @alpine shadow
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.
Given $g:\mathbb{Z}/39\mathbb{Z}\to\mathbb{Z}/54\mathbb{Z}$ is a ring homomorphism, find all values of $g(1)$.
lyric
so im trying to find all possible homomorphisms here, but i think i need help in my understanding
what i have so far is that since we need $g(0)=0$, $g$ must have the form $g:x\mapsto m\cdot x + 54\cdot k$ for some $m\in\mathbb{Z}$ and for any $k\in\mathbb{Z}$, so we can say $g:x\mapsto m\cdot x$
lyric
so like trying $m=1$, im trying to see if thats a homomorphism. we require $g(x+y)=g(x)+g(y)$. so if we let $x=y=30$, how would we define $g(x+y)=g(60)$?
lyric
since g is defined only on $\mathbb{Z}/39\mathbb{Z}$?
lyric
guess it makes sense we'd take the input mod 39, so thatd show g(60)=g(21)=21, g(60)=g(30)+g(30)=30+30=60=6 so m=1 doesnt work
if im right so far, how would i proceed in finding all possible m?

your ring homs aren't required to send 1 to 1?
why would they?
err
that's part of the definition of a unital ring homomorphism
commonly called just a ring homomorphism
because people often deal with unital rings only
anyway
since 1 generates Z/39Z, you only need to worry about defining g(1)
since for example g(2) = g(1) + g(1)
the one requirement is that 0 = g(0) = g(39 * 1) = 39 * g(1)
how are you sure this is the only requirement?
well
think about the ring homomorphism requirements
g(x + y) = g(x) + g(y)
but since every element of Z/39Z is just 1 + ... + 1 a bunch of times
then this will always hold once you decide what g(1) is and then define g(1 + ... + 1) = g(1) + ... + g(1)
similarly for g(xy) = g(x)g(y)

hmmm
i might be lying actually
im definitely lying
g(1^n) = g(1)^n
clearly i never work with non-unital rings
nah
1?
is 1 not a multiplicative neutral element in both?
thats the definition of a unital ring
but not the definition of a unital ring homomorphism
unital homomorphism is what snow's talking abt i think
when you define an object in mathematics, you should also define their morphisms at the same time
so when i talk about unital rings, i really also mean with homomorphisms forced to send 1 to 1
ohh k i got u
anyway
you need this additional requirement that is usually automatic for unital rings
or just like
g(1^2) = g(1)^2 is enough to guarantee that
oh k i can see that
so you're saying any solution x=g(1) to x^2=x mod 54 would give a valid definition of a homomorphism?
alr, so to define a valid homomorphism, it suffices to define g(1) from the fact that addition is linear. then from the fact that multiplication is linear, we have the conditions that g(1)=g(1)^n for all n, and 39*g(1)=0.
g(1)=0 satisfies both, g(1) satisfies the first but not the second, and there are no other solutions to the first
does that sound right?
did you miss something in the second part of the sentence
@heavy plaza Has your question been resolved?
i guess ;-;
ok there has to be a better way of solving this
x^2=x mod 54 => x^2 - x - 54k = 0 => x = 1/2 +- 1/2 * sqrt(1 + 54k) => 1+54k is square => im just plugging in values of k to find square numbers
uh
39x = 0 mod 54 => 13x = 0 mod 18
13 and 18 are coprime so x = 0 mod 18
that gives 0, 18, 36 as candidates
you check their squares and only 0 works
u absolute legend
just tried it on a similar problem (Z/32Z -> Z/100Z) and it's correct
nice
my only issue still is thinking to define g by its action on 1, but from there i can now see how you'd derive those conditions
thanks so much <333333
if you've worked with vector spaces or abelian groups, its essentially the same idea
when you want to define a homomorphism of these algebraic structures, it suffices to say where the generators go
subject to the relations they satisfy
ah i see, i'll keep that in mind when working with them then
indeed
@heavy plaza Has your question been resolved?
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.
how many are in the large circle
80
ok so
there are 3 circles
and two types of balls
@raven hawk u still there?
yes
cool
first you have to figure out what you are looking for
Can u tell me that?
footballs
2
Good, basketballs and footballs
so the entire shipment contains balls
meaning if a ball is not a basket ball, then it has to be a?
a football
Good
interesting
now lets take a look at the diagram
ive never seen a venn diaram like this one
yeah, the not basketballs is fooballs
60
yes, 40 large footballs
good
thats your first answer
now if you have a total of 60 footballs
and 40 are large
how many are small
20
40
Exactly
now the questions asks large basketballs to small footballs
so that would be?
2:1
thanks
Np man
if u have any other questions, u can ask them here, or if ur done just type .close
Closed by @raven hawk
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
why it's 6, but you shouldn't use the help channels to troll 
<@&268886789983436800> troll
algebra
Closed by @formal trail
Use .reopen if this was a mistake.
What if hes not trolling ☠️
Some people struggle in math
I know people in 6th grade who struggle with 2x+6=16
I'd say that's different to asking 3 + 3 since it's basic arithmetic. But ofc people with dyscalculia exist



