#help-17
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Please? I'd like some help.
Whatchu want
Is this correct: $x=(x_1,...xn), V=\Sigma{i=1}^n V_i\partiali$ and $A=(a{ij}(x)){i, j= \overline{1,n}}$, then $V(A)=\Sigma{i=1}^n V_i(\partial_iA)$
Wild123
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Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.
I posted it earlier
can you repost it :3
oh this is easy
$\Omega \subset \mathbb{R}^n$ is an open set, $A, B$ differentiable functions, $A : \Omega \rightarrow M{mn}(\mathbb{R}), B : \Omega \rightarrow M{nk}(\mathbb{R}), u : \Omega \rightarrow \mathbb{R}^n$. $\forall x \in \Omega, V \in T_x\mathbb{R}^n$, we define $V(A), V(u)$ as the differential of A and u along the vector field V.
I try to see if $V(AB)=V(A)B(x) +A(x)V(B)$.
Wild123
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i got [-2 -4 0 1] but my book says the answer is [3 5 1 0 ], [-2 -4 0 1]
can someone help me
define 'null space'
show your work
this is RREF
there is a point where the vector they havve is similar but not the same.... before it is reduced
the -3 -5 1 but they haeve an answer as 3 5 1 0
i have no idea where they got that answer from, do you?
hmm it should only be {-2 -4 0 1] like you said
this is their answer
<@&286206848099549185>
@alpine merlin i did
but whyis this other vector in the book's answer?
idk
what is it asking you to do
What do you do at this point
i wrote it in parametric vector form
then i got my answer..
i got -2 -4 0 1
that is the same answer as the book
but they have the other vector in there also
Show your work
From this point onwards
,w row reduce ((1,0,-3,2);(0,1,-5,4);(3,-2,-1,-2))
They’re wrong I think
this is like the 10th time they have wrong answers in this book
Ok sorry for saying you were wrong
lol aright
This matrix takes vectors of ℝ⁴ by having 4 columns
There’s 3 pivots in the rref
4-3=1
The kernel has dimension 1
So there should only be 1 basis vector
(This is rank nullity theorem)
my university strikes again!
always using the most up to date bs
ok what about this one...
i did RREF
has 0 vector
so x3, x5 are free?
Could be
good enough for me right now
im gona close this and make another one
.close ty 4 help
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how do I solve a differential equation when both sides are polynomials (of y and x respectively)?
the problem has
I have gotten it down to
hold on
1/2p^2 + p = 1/3t^3 - t + C
I don't know where to go from here
could I complete the square with P or something?
omg yeah it would work!
(to clarify, you wanna get p as a function of t only?)
I see it now
general solution
ap calc ab unit 7
Cool, are you given like any initial conditons or anything?
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Im having a hard time trying to figure out how to set up this problem to find the area bounded by this region
or just integrate with respect to y instead
👺
I think you should do it in polar
@winged sigil Has your question been resolved?
you subtract the bottom function from the top function so in this case is it like intergral 2 to 26 of sqrt -(-sqrt) + intergral 2 to 26 sqrt - linear?
@winged sigil Has your question been resolved?
do you know how to do it in terms of y
that would be easier
like y= root(x-1) and y = 6-x/-4?
yes
and then you integrate right-left
so linear - quadratic
wait hang on
actually looks like youre gonna have to do 2 integrals regardless 😭
wait
nh
Im still a little confused on how Im setting this up
sorry
this would be in terms of x
in terms of y it would be y^2 +1 and 4y+6
using this, you could do 1 integral
these are the equations I was given:
y^2 = x-1 and x-4y = 6
have you integrated with respect to y?
Do I intergrate from 1 to 26 with the top function being x = y^2 +1?
when integrating with y its a little different, you do the right most function - left most function
so instead it would be linear - quadratic
but yes, the bounds would be 1 & 26
do you know if your teacher wants it integrated in x or y ?
Whats the reasoning behind this. I just want to know so I understand it better. And would the bounds not change?
okay wait
i am sorry the bounds would be 1 & 5
wait
no
fuck sorry
It doesn't matter as long as you get the right answer. I think she went over something like this before but I forgot how to do it
okay
cause i know sometimes the answer can be different depending on how you integrate
anyway if youre integrating in y, you need to use the y values of intersection
in this case, -1 & 5
the same reasoning with x
i can try to make a visual rq
ok
okay
this is in terms of X
you subtract the top function from the bottom function to find the region
because that is where the areas do not overlap
and its based on area under the curve going to the x-axis , as you see
however, with y
it is this
the area under the curve goes towards the y axis
in this case, the right most function has a greater area
does this make sense?
whos area is the purple the linear function?
purple is the quadratic
linear is blue
here does this help
blue cant be the quad but it goes "above" the function (atl in this orientation)
Oh it makes sense now lol thats the area under the curves
so it would be linear minus qudratic
correct
the area when integrating in y goes from the left of the curve to the y axis
So it in terms of y your intergrating along the y axis and in terms of x along the x axis?
yes, correct
so you use the respective bounds for each. y integration uses y-value bounds
x integration uses x-value bounds
So would the intergral look something like this?
(4y+6) - (y^2+1)
but yes
oh yea
I think I understand it now. Its just hard remembering all the different methods especially with this volume of a solid thing now
yeah i understand, only thing that helps is practice
what calc are you in ?
2

my uni didnt accept my apcalc bc score
so now i gotta retake it
and im absolutely smoked
I didn't even take calc and I regret it now. I took AP stat instead. If I knew it would've let me skip this stuff I would've tried to take it and take it seriously
i only took calc cause i have a hatred for stats bahaha
Funny thing is I didnt even take the AP stat test. I was just taking AP classes to boost my gpa I really wasnt knowledgible about the credits and stuff
I think i was traumatized from pre calc tbh
i dont even remember precalc 😂
its very funny that i cannot remember very basic math things
i was struggling helping someone with limits earlier, people who say limits are easy are fake news
tbh me personally I think pre calc was my hardest my class. Just because you had to learn so many fundamentals

have you taken a trig course, just trig ?
I thought calc 1 was really easy though and I did very well but now calc 2 is like getting hit by a truck
trig is tough for me personally
there is so much to remember
and so many identities
thats why i sorta struggle in calc 2 because there is so much trig you should know lol
well its included in pre calc. but my advisor did recommend me to take a separate trig course which I did but it really didnt help that much
brightside is that calc 3 is easier, or so they say
So far I don't think there's been that much trig or atleast its like the ones that you can find out easily
how far into your semester are you ?
My midterm is on thursday 
Yes and no
She told us to watch a video on it but shes not testing us on it I think
oh goodluck btw, i just took one last week and absolutely bomed the shit
The only stuff I know we have done and been tested on is :
Regular intergrals
Intergral techniques: Partial fractions, By parts, With tables, U sub
Improper intergrals type 1 and 2 like infinity and a denominator going to 0
Arc length
Volume of solids
Some physics thing I don't even remember lol
Area between 2 curves
estimation methods like simpsons rule etc
I might be missing some stuff but I think thats everything we pretty much learned up till now
But its like we skipped past trig subsitution unless thats what intergration with tables is because she was saying something like the tables come from trig subsitution or something
ah okay i see
well im wishing you luck for trig subs, i dont think theyre actually that bad
but personally i struggled
The only indentities that we kind of used are these
we don't use any of the other ones
oh yeah
we use those sometimes
but its mainly like half angle identities and some other random bs
math is so superficial lol
But just like the unit circle atleast me personally I realized I was going about it wrong and I should just remember like the concept of it and solve to the find the other values. Even though it takes me like a lot more time to do a problem I think its better than just trying to jam all the information in and then you have to keep calling back to remember it
@faint pumice whats your major though
i get that
but there is stuff you just gotta remember because the work is absurd
oh dam u gotta take them science classes too hell nah 
I took chemistry during covid in high school and I slept during all the classes during zoom 
Once I heard something about a bond I was gone
my chem class in hs was abominable, an actual fever dream
I still got an A though because I cheated on all the test because the teacher got all of them from online 
compsci scares me
i dont understand none of it
youve gotta take calc 3 then right ?
I warn a lot of people about it. If you don't have a passion for it or your not interested do not take it 
yea either that or linear algebra I think
I still have to take I think differiential equations Im not sure
ive heard that diffeq aint terrible
i believe i have to take linear algebra too tho
not shore
Yea tbh I think the hardest thing is going to be getting through calc 2
Compsci is basically like here's a 1 million people find the fastest and most efficient way to fit them into this small house

its gonna be tough
im gonna lock in though
cause after that exam
i literally am to believe my grade is boutta go from 93 to 65
dead ass
I really want an A but tbh the way its looking we might be shooting for a B lol
I pray for u 
the thing is tho
a B is great for calc 2
ik many people who have taken it at least 2 times
Dam
i believe you can get an A though
Idk man. I lowkey still don't even know how to intergrate using partial fractions 
I never understood that crap
partial fractions are bs
yk that was actually on my exam, and i spent HOURS practicing it
only for a single question to be on partial decomp lol

almost crashed out mid exam
Like it looks like it shouldnt even be that complicated im just slow
And than sometimes Im trying so hard to remember how to use some of these formulas I forget how to do basic algebra
sounds about right bahahaha
look
hang on
@winged sigil
27 mins is insane
i had to do this like 8 times before i understood it
they kept giving me this exact question too
lol looking at that now I don't even think I would know where to start
Do you use webassign too or something different
literally all that was going through my mind is that whoever made this stuff up was fr pullin it out of their ass
I feel like webasiggn is the worst math software ever created
ive not heard of it before now
knewton alta is quite nice, but sometimes i go a lil brain dead and cant seem to understand the steps they skip
Its good and bad because the questions will be so hard and out of pocket sometimes but if you figure out how to do them its easy when theres an exam because the questions the teachers give arent nearly as hard
and chatgpt cant even come in clutch cause its wrong 99% of the time i use it
thats what i prefer
Lol u gotta know how to instruct it properly. But it gets kind of tricky when your asking it to answer estimation questions sometimes
no i swear
this does not work
i have to ask it bit by bit cause it will get it completly wrong when i ask a full question
itll forget stuff moving from one line to another bahaha
or just learn it tbh
its less work in the long run
breuh
i do learn it
i was referring to when my homework software skips steps
i need to see the steps sometimes
I will be doing a problem over and over again come to find out Im just missing like a step or something and chat gpt is good because its there to help explain the thing to you vs u just sitting there not having anything
And when its all said and done Im turning something in vs nothing if I can't figure it out in the end.
sometimes chatgpt is confusing as hell too lol
but i think thats when its also wrong
You can ask it follow up questions like explain further how you got step .... for example.
so for one of these questions i couldnt understand a step it was talking about
and had to ask 3 different times to re-explain lol
@faint pumice u speak french?
My french use to be pretty good but now its down to basic vocabulary and I won't really be able to understand someone if they are speaking to fast
better than me, im still learning. my listening is horrible
whered you learn ?
I went to a french/english elementary school and everything was in french until 5th grade when we started learning english cuz u have to know once u get to middle school
but like no one spoke french outside of school tho everyone pretty much knew english already
you from canada ?
except for like proper grammar, spelling etc
Nah Im from the US maryland
oh thats interesting
makes sense cause its close of french canada but i wouldnt expect the schools to be french-english
Theres a lot of like french/english schools that you can just enroll in
@faint pumice r u from canada or the Us?
@winged sigil Has your question been resolved?
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could someone explain to me why the tangent lines are there? im confused how graphing the tangents of dy/dx would work
is it just because thats where the graph has a slope of -2?
Yea, you can see that the slope of tangent is gonna be negative in only these sections of the curve, and if you eyeball it, then its reasonable to see that the central section doesnt have slope of tangent smaller than -1
ohh okay!! would it still be the case if it asked dx/dy=-2? sorry implicit differentiation kinda confuses me 😭
Once you identify which section is reasonably good enough for this, you draw those 2 lines
dx/dy is 1/(dy/dx)
so you can make suitable changes to guess the correct section
changes = algebraic manipulations
ahh gotcha 🫡 so a slope of -1/2 on the graph somewhere?
yep
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any ideas on this limit?
i think i should be e^n factorial but let me check once
it's + not -, my apologies
take the log
see what comes of that
in fact you will find that the logarithm of this limit will end up being the derivative of f(x) = log(1 + sum sin(kx)) at x=0
(not l'hop)
uhh log of a limit? I'm not sure I know how that works(I'm really bad sorry💀)
was it some sort of formula?
yea there is a method, u put the limit on e^lim then log
sry, nvm this
this is the method, i dont remember the proof, but the limit stays the same if u do this
So, by using this method u can do that
because ln(f(x)) is equivalent to f(x)-1 as x->a
ohhhh I see
I might have seen that before
okay I'll try with that and see how it goes
thanks!
oh yea, thanks
mhm i think u should get e^n!, by using sinx/x = 1 (when x is tending 0)
that would solve it too
something like that?
yea, all the sins change to cos and the x in the denominator will become 1 giving e^n!
whats that power?
yea
and if I derivate each term
yea by chain rule u would get 1 + 2+ 3+ 4+ 5..
mhm = n!
so that's n(n+1)/2?
oh yea
it's not ×
ahh it's okay
I'm just confused 24/ hahah
tha k u sm for the idea
I hope u have a wonderful day😭
its ok no prob
u too
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convergence test
im using 1/n^2 as a comparison test
so if I'm taking the limit, the answer will be convergence, which is 2. Is it correct?
yes
.close
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convergence is correct idk what you meant by 2
LCT 2
oh i didn't know theres numbering on that
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i think the answer to this is (5/6)^3, as p(not getting six) = 5/6
u r correct
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Greetings folks and good evening!
The problem: Find the exact length of the curve y = ln(1 - x^2), 0 <= x <= 1/2
Formula used: L = (a to b) sqrt( 1 + [ f'(x) ]^2) dx
What I am having trouble with:
I am currently stuck at figuring out where to go next.
After getting the derivative of f(x), removing the square root through computation, I am at:
(0 to 1/2) (1 + x^2) / (1 - x^2) dx
I do not know where to proceed from here. Do I start integrating this? Or am I still missing something at this step? Any help is appreciated 😄
can you show your work to get to that integral?
Best I can do is give a photo shot. Give me 2 minutes!
yeah, photo is fine
looks good so far,
you can add and subtract 1 from the numerator to split that fraction
oh wait, that last step doesn't seem right
Yeah the last step is where I'm iffy.
I can leave that and keep to the 2nd-to-last step.
Before I put a negative in front of the integral.
instead of that last step, factor a -1 from the denominator
Only from the denominator? o>o
yeah like $\int \frac{x^2+1}{-(x^2-1)}\dd x = -\int \frac{x^2+1}{x^2-1}\dd x$
dx
Sepdron
then subtract 1 and add 1 to the numerator to split the fraction
Just to be clear, if we factor a -1 from the denominator, wouldn't it make 1 - x^2 into x^2 + 1?
no, if you distribute -(x^2-1) back, you'll get -x^2+1 = 1-x^2
if it turned into -(x^2+1), distributing it back it becomes -x^2-1
Dah right.
1 is positive before factoring the -1.
Ok, so really quickly, am I going to be using partial fractions at this point?
you can but it's a bit overkill
Really?
we're going to achieve the same thing, but simpler
Thank you professor frog
plus keep trying
Gotcha, so I am wondering how you concluded on adding and subtracting 1 from the numerator to split the fraction

im just here to support you guys
here's what I mean\
$-\int \frac{x^2+1}{x^2-1}\dd x$\
$-\int \frac{x^2-1+1+1}{x^2-1}\dd x$\
$-\int 1+ \frac{2}{x^2-1}\dd x$\
Sepdron
Ok got it, but what rule or why did you do this? o>o
I can see that once you split the fractions, you have one that cancels into 1, and then you just add the two +1s together and have the same denominator. I am wondering how you figured that next step from where I was before.
it's a pretty common thing to try to reduce the fraction if the top has equal or higher power of x
Ok!! What formula do you use to do that?
I'm not sure what you mean
I do not know how I would deduce what you deduced.
Because I do not know how you would reduce a fraction if the top has equal or higher power of X.
in this case, you can do this trick
but you can also do it using polynomial long division/synthetic division
But again, I am lost for context for the quick trick you did.
All I can assume that you did is:
Because in that fraction, because the two Xs are equal power (numerator can have a greater X power to apply this trick), you added both numerator and denominator constants only to the numerator.
What I got is this from you:
Apply when: The X power of the numerator of a fraction is equal to or greater than the denominator's X power.
What to do: ???
ok so the goal is to reduce the power of x in the numerator\
since in this case the top and bottom are very similar, x^2+1 and x^2-1
it'd be nice if the top can be x^2-1, since then they'll cancel
but I can't just add a -1 there, I have to compensate with a +1
idrk how to explain it, ig it's just a pattern that you recognize
also after this you'd have to do partial fractions, I thought 1/(x^2-1) was a known derivative
So that is what I am doing right now
First long division, and then on the remainder, do partial fractions
I got 1 + (2 / x^2 - 1)
x^2 - 1 would be (x-1)(x+1)
ig that trick is just a shortcut for that long division
AGH YEP.
I just feel like a big dumb for not knowing
Thank goodness I'm refreshing again on a lesson that's supposed to be one of my tools in my toolbox.
Alrighty, I got it.
The missing step was to refer to Integration by Partial Fraction. First step: Long Division if numerator has a greater or equal X power than denominator. Second step: Do the partial fractions. Compute from there, and it's solved.
Thank you for your guidance Sep!
.close
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Myself.
The person assisting me, Sepdron, implemented a technique that I was not sure how he was doing. I referred back to my notes and figured out that I needed to long divide.
second line, you tried to get the fractions to have a common denominator but you messed this up on both of them by the looks of it
don't call me "dude".
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<@&268886789983436800> transphobe
haylsune miku
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Hii
How are u all?
Not really a place to ask such kinds of questions
Oh ok sorry
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i've got this limit and im trying to figure out what number y tends to
Have you learnt l'hopital rule?
we don't learn that at school
i have heard of it from exercises i've seen online but they don't teach us that at school
so you're looking at $\lim_{x \to 0^+} \frac{\ln(1+x)}{x}$ now, yes?
Ann
yep, thats it
Been a long time since ive done a limit -w-
have you learned about derivatives in general?
i have yes
so I dont have to change the variable?
i was planning on doing y = ln(x+1) to then use the lim when x tends to 0 = e^x -1 / x
which is 1
Oh i get it
brackets
but you could do that as well, only your limit would become y/(e^y - 1) as y -> 0
and then it would be the reciprocal of the derivative of e^t at 0
no, you don't have to change the variable here
yeah, exactly
alright, another question
if i were to change the variable how would I see where y tends to?
if I were to do y = ln(x+1)
$\frac{d\ln(t)}{dt} = \lim_{x \to 0} \frac{\ln(t+x)-\ln(t)}{x}$
Ughh
At $t$=1 is the limit we want to solve
not a rich man
Ah thats smart
not a rich man
@hollow quail ?
it works yeah, thing is since I wasn't taught that way I cant use it on tests
which is extremely stupid
That sucks
Gl though
do you know how to do this?
Were you only taught in school subtitution?
Try Let $1+x=e^{t}$
not a rich man
whats "let"?
Just letting some vairbake equal to a different one
oh yeah sorry, thats what I did
but I can't solve it further without knowing what y tends to
Was the question explictely asked to be solved using subtitution?
You could tell your professor you solved it like this
it wasn't no but in the solutions they use substitution
exactly like Idid
expect they say Y tends to 0+
That isnt necessarily a way you havent been taught unless you havent been taught derivative yet
which I don't understand why
Well when you subtiute in a limit you have to also change what the limit tends to
yeah, thats what im asking
why does y tend to 0+
and not +inf
or something of the sort
ohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
i just replace x with 0 in y = ln(x+1) and it gives me 0
is this it?
Let $y=\ln(1+x)$ , then take $\lim_{x \to 0^{+}}
not a rich man
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Mb for not understanding it correctly
yeah its fine, just glad I was able to understand it now
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ah alrihgt
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Show that for any a, b, c integers, the system of equations (in pic) only has the trivial solution x=y=z=0
I have tried adding the equations together and got something along the lines of x+y+z=0 then a+b+c = 1/2 but I don't feel like thats conclusive
@umbral gyro Has your question been resolved?
<@&286206848099549185>
I think you meant different rather than equal, also, you proved that x+y+z couldn't be different from 0: a+b+c has to be an integer since it is the sum of 3 integers
you can continue from there
you know that -z = x+y etc
@umbral gyro Has your question been resolved?
yeah that was what i proved in the first place, my bad for not explaining it properly
but i dont get this part "I think you meant different rather than equal"
assume x+y+z =/= 0, then you can simplify x+y+z = 2(a+b+c)(x+y+z)
then a+b+c = 1/2 which is impossible bc a, b and c are integers
so x+y+z has to be 0
that's not quite x = y = z = 0, but it's already a good step
also the author's proposed solution says that the determinant of the system must be different than 0 (in order to use cramer's rule), then says the determinant of the system is an odd number so it has only the unique solution (x,y,z) = (0,0,0)
yeah thats what i did
oh I assumed you didn't know the determinant
you can compute it with cramer's rule quickly and conclude yeah
but in class I was told that a linear system of eq that has the results (i dont know what they're called in english) equal to 0 can have other solutions other than 0,0,0
oh okay, i thought it was more of a theory-oriented question, not simply computing the result
if you calculcate the determinant, you find (2a-1)^3 + 8b^3 + 8c^3 - 12(2a-1)bc if I didn't make mistakes from head
i think we got the same result
i wrote it differently
computations are just applications of theorems hence proofs as well
oh no I made a huge mistake (corrected)
you can do computations as a proof as long as you invoke the relevant theorems correctly
did u do RHS = coeff matrix
👀
,w det[[2a-1,2b,2c],[2c,2a-1,2b],[2b,2c,2a-1]]
which makes (0, 0, 0) the unique solution
that makes sense yeah
i've have made a mistake somewhere as i got the det = 8* ( something ) without the -1 part
thanks guys, that answered my question
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is this actually the answer? because i got arcsin(x/2)+x/sqrt(4-x^2)
They're the same; tan(arcsin(x/2))=sin(arcsin(x/2))/cos(arcsin(x/2))=(x/2)/sqrt(1-sin^2(arcsin(x/2)))
oh wait, did you get **+**arcsin(1/2x)+x/sqrt(4-x^2), not **-**arcsin(1/2x)+x/sqrt(4-x^2)?
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Did I find the area correctly? If not, where did I go wrong?
12 is correct.
Alright, thank you so much!
yeah no problem
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i might’ve forgot the -
but that would only make me lose a point
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Question about the term divergence test
The test say if the limit is not equal to 0, then it diverges.
but doesn’t a finite existing limit mean that a series converges??
the limit of the term and of the serie are two different things
if you sum a sequence a_n = 1/n²
a_n goes to 0
and the sum of the a_n to pi²/6
What do you mean the limit of the term?
lim a_n
Am I not using the series when I use tdt?
I thought it converges when it has any finite limit?
limit doesn't mean anything if you don't say limit of what, yeah convergence is having a limit, but a sum having a limit and the sequence having a limit is obviously an entirely different thing
as one of my teachers would say, you're using vocabulary in an accident-inducing way
careless is the vocab 😉
well, I tried my best to translate the wordplay from his language
Can I add u in case I need help later
no, but you can ask for help here and ping helpers (or me)
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For any function f : R → R, there exists a differentiable function F : R → R with F
′ = f.
what if its not continuous
so if F is differentiable, it must be continuous everywhere?
yeah obv. but like im talking about f
what if f is not continuous
sure
i dont see how it relates tho
if f is not continuous somewhere then it is not differentiable there
what about $f(x)=1$ if $x \in \mathbb{Q}$ and 0 if $x \notin \mathbb{Q}$
tm
but the question doesn't ask about derivative of f
its also non integrable
wait nvm i g there are funcn which are integrable but not continuous
oh but ig if a function whcih is not continuous because somewhere it goes to infinity then it is not integrable over that point right
like 1/x
or am i wrong
yeah basically any function that cant be integrated fits as a counter example by taking it as f and naturally F does not exist
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could someone explain why the correct answer is b? i tried using the definition of the derivative but this is what i ended up with
what did you get as f'(3)?
using power rule isnt it just 12?
i mean im not surprised if it would work backwards but im not sure how to get there
they use a different definition
substitute a = 3+h
same limit
are they using f(x)-f(a)/x-a?
that makes a lot more sense 🫡 i was wondering why i couldnt find my answer
maybe should use something else than x
ty for the help!! :> i think i got it from here, i completely forgot the other one existed
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Does someone know why The Constand isnt added in the this step of integration
the integrals are implicitly assumed to come with +C
theres no canceling of c's
just keep in mind to put +c after any one of these integrals
$\int vdu+c_1+\int udv+c_2$
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is that constant the same as uv's consatnt
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if u have integrals on both sides of an equation, just subtract one side
$\int f+c_1=\int g+c_2$
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So the C's do cancel
$\int f=\int g+C$
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these are not the same c's
these are just individual rules for combining constants of integration
they can always be added or moved to other sides
in the end u always get a single constant on one side
but where is uv
$uv=\int vdu+\int udv+C$
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I understand the other side has a constant but since when does that let you remove uv's constant
from here
but I thought that the intrgral of 1 was x + c, not x
but then why in indefinte integrals do people only add c after doing the integral and not before
thats literally how i describe how indefinites are done
you add c because when you differentiate you lose information - the constant terms 'disappear' so when you integrate you add a +c to account for those constant terms
when its the integral form there's no need to have a +c
so c is accounted for in the integral but is loss when you do the integral so you have to add c again
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but i wont actually do that, its tedious
and the constants can be added to make a single constant
so we dont bother adding a constant til the very end
I was just confused why consants were added but the integral wasnt evaluated
$x+x^2$
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ok so the integral is just the antiderivative
thats exactly the same thing happening in ur pic
thats why most books dont bother writing +C every time
its implied u will write +C at the end anyway
ok thank you
ur welcome
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We're attempting to solve part C, so we have [P(x = 0.21) = \int_{0.21}^{0.21} 1(1-0.5x) , dx = 0]
I'm a bit confused should we have gotten zero there?
Ryan + James (TCC)
Oh wait my book tells me
oops
well uh...amended question then, intuitively, why can't we say that that some event will occur with a specific probability then
can u summarise the q
u can, it's 0
yeah ig that's what I'm confused about, why can we say there's a probability that an event can occur over a range but any specific value is just zero if that makes sense
I can see it mathematically but it feels a bit unintuitive ig
yes that is normal
probability 0 does not mean impossible
nod
So I guess this means that we have a "higher chance" of our value being in a range rather than at any given specific value in the distribution?
well yes
it has higher probability
are u familiar with the measure theoretic formulation of probability?
Vaguely
Just with the definition of a probability space and measure, no further than that
this issue can arise when ur sample space is uncountable
cuz the probability measure is only countable additive
ahhhhh
ex if it's R?
uncountable additivity doesn't make sense in this context afaik
like uncountable sums
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do group actions have closure by definition? Like does $gx \in X \quad \forall g \in G$?
im asssuming this is the case
BOSS
absolutely.
And thats not like a proof, its legit just the definition of a group action?
I was asked to prove it for a problem so im curious if i can just write By Def
if you have to show a specific thing is a group action, well yeah you gotta actually prove it, it's part of the definition
Ah, so above the identity and associativity I have to always prove closure?
Legit the question is "Prove that group actions meet closure"
Its a prelim so they are usually easy, I jsut wanted to make sure its something I can say
"by definition"
pretty odd
but I'm not asking about the question you have to solve, I'm asking about the defn itself
@hearty delta Has your question been resolved?
ah sorry
yea u gotta show the actions actually maps into X
G x X --> X
if the action is transitive and free the X is called a G-torsor
which are the fibres of a principal bundle
what does this mean
$ \pi: E \to X$. $ \pi^{-1}(x)$ is a $G$-torsor for all $x$. There is a free group action $G$ on $E$, whose orbits are the fibres
martingale
ah
ok
Sorry working it out lmao
Really quickly, are all points in an orbit distinct?
Thet would have to be right
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For part (ii). Ik that that the max occurs at x=2, but how to find the y value
Do you know how to find out if f(x) is increasing by looking at the graph of f’(x)?
yeh
So which values do you think it would be increasing on?
Oh sorry you already noted that
Maxima and minima occurs at zeroes of the graph.
yeh, x=2, what is y though
When the graph goes from positive to negative, its a maximum, and if it goes from negative to positive it as a minimum
So you have to test that and the endpoints as well
Does it ask for the y-value? I think you could just say it occurs at x=2
Ah i see
You would have to use integration
From 0 to your max x value
Remember your formula for it
F(2) = f(0) + int from 0 to 2 of f’(x) dx
integral of f'(x) is just f(x)
Integral of f’(x) is also represented as the area underneath the graph
Therefore thats also the reason why the area under the graph is given to you
Does that make sense?
Yes
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for part (e) I'm still debating whether it's
$1 - e^{-\rho}$
dXₜ = μXₜdt + σXₜdWₜ
dXₜ = μXₜdt + σXₜdWₜ
<@&286206848099549185>
No idea
dXₜ = μXₜdt + σXₜdWₜ
dXₜ = μXₜdt + σXₜdWₜ
dXₜ = μXₜdt + σXₜdWₜ
@deft vapor Has your question been resolved?
@deft vapor Has your question been resolved?
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This is good but what is this??
@charred sierra Has your question been resolved?
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can someone help draw a diagram I have no idea how to
i cant help too much with this because i dont wanna give you the wrong help. but i can tell you for sure that an angle of depression goes down from the origin
so your 25 degrees would be 25 degrees south of east
same with the 33 degrees
oki thanks
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Hello
I would like some help
<@&286206848099549185>
I've tried to find the similar sides
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Hello is there something wrong with my process or is this fine
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how do i start this question, i dont know any process to begin with
@wheat garnet Has your question been resolved?
<@&286206848099549185>
yeah idk man
vectors are confusing
draw it?
i just look around and see if i can do it
if i can, i help
in terms of questions.
<@&286206848099549185> sorry for the double ping
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