#help-10
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LaTeX on phone. 😢
yes thank you thats what i was thinking it makes so much sense thank so much
Good luck in your computations. 🙂
hahaha im sorry to make you go through that thanks for all the help 🙂
Glad to help. 🙂
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Im so confused
Is this the graph the derivative of a function?
Can you show us the directions too otherwise we have no idea
@timid silo Has your question been resolved?
Ok this is the graph of the derivative
So when the graph of a function has a critical point, what is the value of the derivative?
0
So when is the graph of the derivative 0?
At those numbers
-1, 4.5
and -5
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i need little help
yeah
i need to arrange it
1- (cos(x))^2 = ….
but i dont know how
.
sin2x
luka are u familiar with cosine double angle identities?
1 - sin^2(x)
no
2sin^2x
yes
now you can simplify the sin
yes
okay
c
x
yeah
but i wrote that on photo math
easy
HAHAHAHAHAHAHAHA
what
💀
Stephen
you get 1/2( x+c)
yeah
yes
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Hi can you help me with this problem please ?
let us see
are M_{n,m}(K) the matrices of size n-by-m, and rg is rank?
@balmy atlas Has your question been resolved?
if you have rank 1, what can you say about the relationship between the rows
what about the columns
in a product CL where C is a column and L is a row, what can you say there
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Help
Does anyone know where I can learn to solve this problem I have never seen it before and I don't see similar example on yt
are you doing 4?
just solve it case by case
IF X >= 2
and then
IF X < 2
Okay I have a few questions about that but what does
|X| do here?
To add the two solution
,w plot |x|
,w plot x
So I find what the solution is
IF X >=
lets say its 2
And IF < 2
lets say its 1
And then I have to add them
So solution is 2+1 =3
you do not add solutions
you're only looking for solutions to your equation
they do not add like that
Well they told me to find
x for both cases and add them for some reason
show the question
Okay one sec let me translate it
But it just says
Find the
the sum of the solutions of the equations
Let me write the solution on paper
then this is correct
Okay let me see if |X| is needed here
And I to find a way to ask this question in a way that makes sense
looks good
Okay here , so I don't see |X| interacting with anything in this problem so I don't really see the point of its existence
So do I just say oh in this problem I found |X-2| and then go , okay I was given some rules for x-2 let me look at them .
And since there is no |X| in
|X-2|+X×2:3-4=0 I literally just ignore it since it has no reason to exist
|x| is just compact notation
that's like saying $\pi$ doesn't have a point for existing because you can just say "number equal to the ratio of a circle's circumference to its diameter"
riemann
Okay so will there be a problem that is being changed by |X| practically,I will read more on it soon but for now do I have to ever look at |X| while solving problems like this one
what do you mean "do i have to ever look at |X|" ?
are you asking if you have to read the equations you're being asked?
then the answer is yes
Really I just feel if I ripped the |X| part from the paper and did this:
Find solution IF X >=
Find solution IF < 2
Add the solutions
My solution will still be the same
will still be the same as what method?
As the method where I did not tore the |X| out of the paper in this problem
well yes they're mathematically equivalent because that's just the definition of |X|
That is interesting Eve if I did something like this?
Or is it more something like pi where you cannot change it
i have no idea what you're even doing here.
no. you cannot change the definition of |x|
Oh okay so it is literally saying
Pi = 3,14 at the start of every problem involving pi
i don't know what you're saying anymore
just do a new problem
Thanks I got it will read more on WHY X is like that but for now just knowing that it is like that is enough
a good start
https://en.wikipedia.org/wiki/Absolute_value
Yeah that looks like it will explain it thanks a lot! just have to take a break my head hurts a little I should sleep more than 4h
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any idea on how to start this problem?
i tried to parametrize it but idt it's the right approach
anybody?
i just need a little hint and i think i can solve it on my own
@rustic heath Has your question been resolved?
@rustic heath Has your question been resolved?
@rustic heath Has your question been resolved?
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hey, for any people good with trigonometry, i had confusion in regards to two different answers
the two images have an answer that is 60 degrees (pi/3 rad) vs another answer that has 30 degrees pi/6 rad
my first question in the first image had a regular triangle that i drew as its supposed to be in the answer
in the second question however, i made the same similar shaped triangle and assumed it would be an equilateral triangle (which was right, but the execution was wrong?) because the triangle was the other orientation and was facing upwards
why is it suddenly 60 / 2 = 30deg? it was just a bit jarring to me even after reading the answer explanation
@timid silo Has your question been resolved?
<@&286206848099549185>
@timid silo Has your question been resolved?
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Is there a nice limit for this sequence of functions? Can I use l'hopitals
I have brain rot
b) for full q
i have dominating g I just am too ??? to get f_n -> f
nvm
i have brain rot
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I am having a small confusion about the notation Rudin uses. In chapter 2 he mentions that (a, b) is open in R but not in R2. First one is immediate but I don't understand the second one.
Is (a, b) like an open rectangle in R2?
He generalises closed intervals in higher dim spaces as k-cell. So, a 1-cell is an interval, 2-cell is a rectangle and so on...
Someone on math.stackexchange said that we have to identify (a, b) with (a, b) x {0} to view it as subset of R2
But Rudin never mentioned anything even close why is why I am confused
That, p is an interior point of E if there exists some real number r>0 such that Nr(p) is contained in E. If every point is an interior point then the set is open.
Yeaah
ah. So Rudin is basically avoiding using some clunky notation.
The interval (a,b) is open in R because you can put a ball in it (other open intervals)
The interval (a,b) is meaningless in RxR unless you think of it as a line from a to b. or (a,b)x{0}
if you want it to be rectangle in RxR then you need a second interval for the 'height'
So (a,b) doesn't have a height, it's just a line.
I thought that a and b are 2d coordinates specifying the width and height but it seems I was wrong
Like a=(a1, a2) and so on..
Ah, nope. He's literally saying 'the one dimensional interval (a,b) in RxR"
basically, yeah
Alright, thanks ❤️
the intuition is that the line (a,b) in R is the same one dimensional line in R^n
@unreal musk thanks for the reacts, very helpful 
Hey, Rudin is amazing, yea 
What edition are you using? I don't see this notation in my version
3rd edition
Oh okay, I have a 2nd edition
I heard 2nd has worse notation lol
Plus for cheap SEA version 3rd edition was the only one I could get
Mind you, they do say "if we regard it as a subset of R^2" (and the way C and R^2 seem to be identified there!)
Well... its from the 60s and does have some pain associated with reading any math book from that era
Hmm... I thought it would be something like generalisation of segment in higher dimensions
segment 
Ah, like the k-cells but open instead right? 
then it would be a rectangle 
Yep
Yes I was thinking of open rectangles as it's more natural

I thought maybe there's some problem at the corners but now that I think about it open rectangles would be open
it would be a bad name otherwise 
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ok so
shit it didnt send
one sec
im basically just unsure if i did what they asked me to
or if i'm missing something
or if i did it right in general
Seems justified to me
,w Limit[Sum[(6/n * 1/(6 k/n + 1)), {k, 1, n}], {n, Infinity}]
It broke 
Seems fine to me
@idle spade Has your question been resolved?
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question b
!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'm told it's wrong
4. I got an answer and would like my work checked
5. I have a question about someone else's worked solution
6. None of the above
Show your work
it’s 7.8
_ _
@north forum "show your work" does not mean "blurt out another answer"
yeah i know, i am trying to do it again because i did it on my calculator
and my working out went
i did
this
261.8/2
which is
130.9
130.9= 1/3 pi h r^2
(130.9 times 3)/pi= h times r^2
where did 261.8 come from...?
,calc pi/3 * 5^2 * 10
Result:
261.79938779915
okay, checks out.
asterisk for multiplication
oh alright thank you
what did you do from here?
do you have your work written out on paper?
yes but it’s messy
it's hard to decipher what you are doing from this fragmented retelling
this seems like it is not your full work
i’ll send it all to you
I'm assuming what they did was they got $V = \frac{250\pi}3$ for the full volume. And then since $\frac r h = \frac{1}{2} \implies r = 0.5 h$, $V = \frac{h (0.5h)^2 \pi}{3}$.
Umbraleviathan
But then you need to solve for h when it's V/2 instead of V
hold on
You did hr instead of hr^2
And even then, you'd need to solve for r in terms of h
that's why r/h = 5/10 implies r = 0.5h
Since the volume of the full up is 250pi/3
You don't even need to solve for the radius
Just replace r with 0.5h
The half volume would be 250pi/6
what about the square root?
There should'nt even be a square root
If you replace r with 0.5h and the volume with half-full volume:
$$\frac{250\pi}6 = \frac{h(0.5h)^2 \pi}{3}$$
Umbraleviathan
As a helper, please do not give out answers that could be copied as a homework solution. Have the student work through the problem themselves and guide them along the way.
Did you seriously nosols me lol
Nah EndTimes just popped in
i swear to god
yeah
So I don't understand where the square root comes from
I want you to simplify the numerator of the right hand side
would it be 0.25h^3 pi?
h would be 5.5
Algebra
yeah so you did
$\frac{250\pi}6 = \frac{0.25h^3\pi}{3}$
Umbraleviathan
i didn’t get that
i did
what you did
but didn’t divide by 3
because i forgot the original question
<@&286206848099549185>
what?
i got 7.9
second dont ping helpers until you waited 15 min
man.
Yeah that's close enough
They probably did intermediate rounding
Or they curtailed the number
Yeah if you do intermediate rounding, it's 7.8 something
7.9 is more accurate
i thank you so much and i am so sorry for the hassle 😞 you’re so helpful i really appreciate it
Np
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Where do I start?
By solving the differential equation first ??
do you know how to do seperable ODEs?
no
Did your class cover them?
Group all the ys with the dy and all the xs with the dx, and integrate both sides without limits
That's the general method
For ODEs that are seperable
For seperable ODEs i.e.
alright
What knowledge do u have of differentential equations ?
Don't forget to add the constant of integration btw
and realize that you can group constants at the end
ln|y| = -xcos(x) + sin(x) + C
NEONPerseus
y^2/2
,w int xsin x
yup with that correction you're good
now put in the values for x and y to solve for the constant
C= 81/2
,w solve dy/dx = (xsin x)/y if y(0) = -9
So the answer is just the value of C?
NEONPerseus
this?
oh yea
Replace c with the constant calue
Hi obchusegoose
hello
When are tou starting to help others
how come c is 81?
not in a while, i suck at math
Us 
No problem
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I just multiplied both sides with 2
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does someone mind explaining how f(x) is = y. I can't really comprehend why
yeah cause it isnt a Rule™️ or anything
it is simply common sometimes when talking about a function to write the letter x for its input and y for its output, but there is really nothing special about those letters from a formal pov
Oh really?
I thought there was some theory behind it
And explanation on why because my teacher said something about it and couldn’t really understand
@proper narwhal Has your question been resolved?
there is none
y is just a function of x
f(x) means a function of x
so y can be the same as f(x)
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Is there any value in using matrix algebra as opposed to normal elimination/substitution techniques in solving 2 variable linear equations? Or is it always much more efficient in using normal algebra for 2x2?
2x2 it doesn't really matter I would say
I know that with more variables, matrix algebra becomes more computationally fast. But what about just 2x2?
you are doing the same steps, just slightly less writing down
cause you dont have to write down the variables
If you have to repeat the same techniques with changing constants and coefficients, then what it become simpler with matrix?
or still the same?
still a 2x2
if you are just talking about row reducing, the matrix variant is really just a different way to write it down
imo a better way cause you only write down the coefficients and there is less chance to mess something up with the different variables
but in the end its just a different way to write it down
and of course with matrices you get all the theory from linear algebra
Oh ok, so it's the same efficiency in all 2x2 cases?
well you are doing the same steps
whether you subtract the first row in a matrix from the second or the first equation from the second doesnt make a difference
same result
latter is just more stuff to write down cause of the variables
ah ok, so it would only start to make a difference with more variables?
well more variables means more extra stuff to write down
already in the 2x2 case you have to write down more stuff
but really thats the only difference
@worldly trench Has your question been resolved?
I need to find the fraction
Decimal = 0.2777
Fraction = ???
Perfect = 27.77%
I need to find the fraction
Decimal = 0.2777
Fraction = ???
Percent = 27.77%
@fossil stump #❓how-to-get-help
This is someone else's help channel, please grab an available one
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When does the equality hold true for integral form of triangle inequality? I'm dealing with real valued functions
:
do you know when equality holds for the usual triangle inequality?
yes
which is when?
when all the 3 points lie on the same line
3 and -2 certainly lie on the same real line
im dealing with distances no?
-2 is not a distance
the usual triangle inequality for real numbers goes like
[
\abs {a + b} \le \abs a + \abs b
]
oh, i just relate it with the usual "triangle
And consider |a+b| as one distance
and |a| , |b| as the other two
sides
so when a and b are the same sign you mean
alright, so do we have the same continuation for the integral as well?
int f(x) . int(g(x)) should have the same sign, both going from a to b?
do i consider int f(x) * int(g(x)) >=0
no the integral itself is already a kind of sum
so you want f(t) to be the same sign for almost every t
we dont consider the limits?
almost every t within the limits lol
the limits are just a fancy way of saying you're integrating over the whole real line the function 1_[a, b] times your function
or is it the other way around? hmm idk but whatever lol
ye
yeah okay nevermind that thing doesn't work so nicely for Riemann integrals
when i said almost every t obviously i meant the ones that mattered
but yes almost every t within the limits
wait can i get help over this example so i understand it fully of how i should use this equality?
isn't that jensen's inequality or something
consider this:
$$ \int_{\frac{\pi}{4}}^{\frac{5\pi}{4}} { |(\sin{x})-a|} \geq |\int_{\frac{\pi}{4}}^{\frac{5\pi}{4}}{ (\sin{x})-a}|$$
saltyballs666
equality holds whenever $$\int_{\frac{\pi}{4}}^{\frac{5\pi}{4}} {(\sin{x})-a}>=0$$
saltyballs666
well certainly the function being nonnegative a.e. is sufficient to ensure they're equal
ok thank you i have got it!!
but hmm I'm trying to come up with an argument for why it's necessary but I'm sleepy
i think the normal discrete analog makes sense
like i can't really derive triangle inequality for integrals, i just know it works since its the continuous analog for discrete stuff, we arent taught Riemann sums yet, we are just told to know that since it works for discrete, it will work for continious too lol
oh yeah it's because the integrals are equal on the positive parts
signed area?
so if it's negative for some non-negligible set
then you're never making up that difference
makes sense
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i used mkdir to create new directory y9 and then i want to create a new file called myfile inside y9 how to do it
this is a math server lmfao
@rough parrot Has your question been resolved?
bruhh
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help
whats the question
image on its way?
is the 14 answer to part (a) written in by you?
is wriiten by me
because
thats the start
do you need a clearer photo
clear picture
me waiting for help
sorry, was called away for a moment.
At the time of death, a particular plant has 100 units of carbon-14 in its tissues.
the "14" in carbon-14 is, for the purposes of this problem, simply a name. it is not a piece of numerical data for you to work with.
oh okwy
have you started on part b or are you paralyzed by it
paralyzed by it for sure
ok do you know what a halflife is
geussing 50% of the plants life
incorrect
and you do not need to guess
if you don't know then say you don't know and i'll point out where in the text it says what the word "halflife" means
the time taken for half of the original amount to decay
or to put it another way, the halflife of a radioactive substance is the time during which said substance shrinks to half of its amount
okey i understand
can i ask you now to write something down in symbols
yes i can
\textit{read these instructions to the very end before proceeding.}
referring to the formula $$Q(t) = Q_0 e^{-kt},$$ and knowing that the halflife of carbon-fourteen is $5568$ years,
write down an equation (but \textbf{DO NOT} manipulate, rewrite or simplify it in any way) that states:
\textit{``The amount of carbon-fourteen remaining after 5568 years is half of the initial amount.''}
use the letter $Q_0$ for the initial amount; \textbf{DO NOT} replace it with any numerical value.
if you have read and understood the above instructions, send the message ``Okay, I will work on the equation now.'' before proceeding.
Ann
okey lets look at this
okey
Okay, I will work on the equation now.
was the initial amount 100
@royal basin
use the letter Q_0 for the initial amount; DO NOT replace it with any numerical value.
no, this is only the general radioactive decay equation
you have not yet written down what i asked you to write down
The only variable in your equation should be t
Well I suppose initial amount is also a variable…
oh okey
the "half of the initial amount" is missing.
@grizzled shore you might be misleading here a bit
Ok I’m just gonna hush I feel like I’m not helping at all
your feelings are true
@glossy yew Q(5568) = [half of the initial amount]
that's what i want you to write down, partially paraphrased
can you put it entirely in symbols
what symbol did i tell you to use for the initial amount?
wrong on both counts.
okey
do you have problems with reading comprehension?
kinda
yes it will
Ann
oh
and THEN i would have you write down $Q_0 e^{-k \cdot 5568} = \frac{1}{2}Q_0$ and walk you through solving this equation for $k$
Ann
i do not know what you mean when you say "elimination"
the next step would be to divide both sides by Q_0 unless you want more headaches
What the actual
yah like thats my expression
e^-k5568 = 1/2
e^(-5568k) = 1/2, yes
do i flip it and turn it into to a log?
so log e ^1/2 = k5568
no
what
@glossy yew Has your question been resolved?
you tried to take the logarithm of both sides (i assume) but you fucked it up
or maybe you did not write it correctly
you should have ended up with $-5568k = \ln(1/2)$ perhaps
Ann
it's ln (lowercase L, lowercase N) not "in".
okey my bad
so now that we got k
whats next
@royal basin
bro we already solved it
bro im a monekey
that hasn't envo
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How do i find what z is, in my class we have only done trig sub where z does not have a coefficient
i see how the solution works i just want to know how to come to the conclusion ig
You cannot solve for anything given no statements (An expression alone provided zero information)
this is a trig sub intergral
Ah, so you are integrating?
yes I am sorry
If the sub is unclear, consider factoring 4 out
You should get 2sqrt(1 - 9z^2/4)
You may also notice this is the same as 2sqrt(1 - (3z/2)^2)
Meaning you can do 3z/2 = sin(t) for example
i think the idea is to sorta play around with it so that you are able to factor it out into something that has a perfect square root and then the trig identity right?
i was doing another trig intergral where it was like sqrt(13 + 25x^2)
Yeah, after some practice it will become obvious that the sub is z = 2sin/3
and the solution subbed in sqrt(13)/5
Yeah
You mean changing the bounds of integration during a sub?
I mean like putting the final answer in terms of x and not theta
Ah
E.g. z = 2sin(theta)/3 means that theta = arcsin(3z/2)
Just use inverse trig functions
when does the pythagorean come in
like for instance if you had cos theta right
you would have to solve from theta = arcsin to get cos
Like how would you get cos(theta) in this case?
Or how to simplify cos(arcsin(something))
oh sorry instead of using inverse you could just san that 3z/2 = sin theta and then use the triangle and pythagorean theorem instead of directlky subing in the inverse right?
Yeah, if you want to evaluate some other trig functions of theta
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LCM is 4x
what about 4x
4x works too
why did you tag on the x
Doesn't really matter
If you just multiply by 4, you can't get rid of the x in the denominator
Remember, 4 is not divisible by 2x, whereas 4x is divisible by 2x
both sides have been multiplied by a common (here 8x) so the value of x remains same
It is mostly done to cancel the denominators and make the calculation easier
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,rotate
Hey guys, wanna ask for help. Maybe you know a yt vid relating to this topic
is 't' not defined anywhere else?
like is all you know about t that it is parallel to the line y?
Also its f, sorry for my handwriting
this question is oddly minimal in the information it gives
presuming f isn't a straight line, where a tangent would be redundant, the phrase 'the tangent line to the graph of f' is an odd statement
you cant give a tangent line of a graph
you give a tangent line at a point on a graph
Our teacher says that just from that, we could tell that m=1/2
i'll presume the question is trying to just teach you about parallel lines, then
if something is parallel to another straight line, it shares the same gradient
this is how they arrived at this
btw, our lesson is about Intuitive Notion of the Derivative
How?
if two straight lines share a gradient, they are parallel
you are told the tangent is parallel to y = x/2 + 5
the gradient of y = x/2 + 5 is 1/2
so the gradient of the tangent must also be 1/2
Ohhh, but how do we use this to find the equation of the tnagent line?
a tangent is a straight line
so it is of the form y=mx+c
you know m = 1/2
you cannot determine c without any further information
=> y = x/2 + c
So Is it unsolvable?
.rotate
,rotate
,rotate
wheeeere are you getting f(a) = sqrt(x-2) from
if that is what f is you should've just said lol
you're also getting
'find the tangent at point x=0'
out of nowhere
i don't think you've written it out, correctly
your question should be akin to
(Using the limit definition of the derivative/gradient), Find the equation of the tangent to the graph f(x) at x=X)
I did write the question properly, my teacher mentioned to refer to the given formula where lim is ∆x->0
this is from this equation
the limit definition of the gradient at point a
in your question, you did not provide f(x)
yet it seems to be defined enough from the limit written above
Ohhhh
if you did not have a f(x) writing sqrt(x-2) and sqrt(x+Δ x-7) would be impossible
so you do, the question is just missing information
Ohhh, thank you
So the missing info is just x=0? Which is already there but isn't mentioned?
.close
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help
Sum of what?
p^2q/r + p^2 r/q + q^2 p/r + ...
Ok so it's different permutations
yes
So show your work
this is what i got after expanding the summation
p^2q/r + p^2 r/q + q^2 p/r + ...
also the info i have is
p+q+r = 2/3
You must've the roots
im sure we need to use these to find the answer
Alr
So (p+q+r)(pq + qr + pr) = p²q + pq² + pqr + .....
But after this gotta think
Ok anyway find this expansion and put -1/3 for every pqr and equate it to 0
3 equation 3 unknown u can solve them
yeah i also tried making the numerator same
ig i'll just have to put in the values of the roots
Then we can go ahed
Did you try this
ok one second
Tell me what you get
ok i got this this
$$p^2q + pq^2 + q^2 r + qr ^2 + p^2r + pr^2 = 1$$
Yes
so did u find anything
hi
hi
need any help?
yeah
this
Nu
that sucks
wait wdym summation of p2q/r?
@timid silo
Thought you'd figure it out
ohkk
Feeling sleepy rn
ur supposed to use this @timid silo
-b/a
i wrote all of that stuff above, im just having trouble factoring this thing
ok imma find the roots
just take t = x^2
no that doesnt work
so 3x^3 = 3t^y
whats y
what are u trying to find
why are u using t^2
it wont be a quadratic
yeah now u cant write the x term in terms of t
ye sed
also i can solve the cubic
but thats not the issue
we not to use the sum of roots and stuff..
thats the problem
,w solve 3x^3 - 2x^2 + 1 = 0
yeah i dont think we are supposed to find the roots lol
nope
aight
ok
so im taking common
brujh
still not getting anything soo useful
wait a sec
ok denominator cancelled
so finally im getting this
3(p^2q^2r - 2p^2q^2/3 + p^2r^2q - 2p^2r^2/3 + q^2r^2p - 2q^2r^2/3)
u multiplied by pqr then put it = -1/3?
not exactly but
somewhat substitution
bruh
its coming like infinite loop
i've simplified to max
is the answer 3/4?
idk what the answer is
lol
this is so dragging man
do u mind asking ur teacher or smth?
cuz idk after this what to do
aight but i doubt they'll respond rn
nah man why u saying sorry
thanks for helping
yenn
now we have
yenn
so we just need to be able to compute $\sum{1/x}$ and $\sum{1/x^2}$ to get what we want
if i havent made any mistakes which you can veryfy, now all the variable algebra is done and you're left with just numbers
here I merged x^3y^2 + y^2x^2 as x^2y^2(x+y) for all pairs (x,y), (y,z), (z,x)
yenn
@mental fiber you can analyse it if you want
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Alright so I just wanna make sure I'm on track with understanding Big-O.
If I have something like f(x) = x + O(x^3), this means that f is asymptotic to x^3 or something like that?
Because I came across this a month ago and decided to read about it on google
And then it came across me again and now I'm like "O"
'o'
And asymptotic, I mean that the remaining terms remain beneath x^3
So like
Something like that
And so does this mean that f(x) < x^3?
Oh I see
< M x^3 for some constant M
Hm
so like 2x^3 = O(x^3)
yes
But not x^5 = O(x^3)
it's also O(x^n) for any n≥1
yup
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How can I solve (1-x)^2 by u substitution?
Would it be u^3/3 ?
yes
I got -du, looks weird
its not weird
oh yeah it will be -u^3 / 3
ah
then you have to substitute back
^^