#help-36
1 messages · Page 290 of 1
oh it is 2 parts
so actually
you can write x y and z in terms of a third parameter, say t
since its one dimensional
but what you have is also probably fine
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Idk how you would make t the correct parameter
Since I don’t see any easy way to sub t = some combination of x y and z
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… now we getting I to stuff idk so I think it’s best to leave it
bro but i think your answer is not final though
i can already see the answer
i forgot about it until now
it is but its not an explicit expression
for x y and z
if you can solve an explicit expression you usually should
and in this case its actually not that hard
if this is calc 3 then thats what they would usually expect
It’s vector calc or whatever we’re doing
Yea
But it’s also not calc 2 or 3
Our unit is just “vectors in 3D and vector calc in 2D”
So what we have is fine for the level im at
And I’ve gtg soonish so I don’t have time to do much more
Just expand the answer I got at the end
will u be here in like a few mins
Uh probably not, I’ll be here later today more than likely
Ty for the help, I’ll look into parameterisation when I get the chance, since it sounds like it simplifies the answer more
Dude is doing Specialist Maths 🥀
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They didn't, I edited the ping in.
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I need help idk how to do thks
try finding a formula?
Well ik we must use the inf geometric one
say, total distance traveled when it hits the ground for the N'th time
first, when it says its thrown out the window from 24 feet, what is the 1st term?
Thats the "problem", the first term isnt part of the series itself.
Consider, for each bounce, the ball goes up and down, making the same distance twice.
Except for the first one, where its thrown directly down
this is why its confusing
the easiest way imo is to track the first down, the first up, then find you series based on that total distance
destiny
uhhh i dont need sigma notation for this problem i dont think
no, you dont, but if youre using a geometric sequence, you are anyway
ok so then explain what i should do
How else did you learn to sum an infinite number of terms
first term over 1-ratio i think
This kinda assumes the final bounce's covered distance tends towards 0 as i approaches infinity, does that mean extra work?
Well yea that's only after you get the infinite sum using sigma notation here
what
yall are confusing me i should mind aswell ask ai or something
ok have fun
what do you know about geometric series?
geometric series multiplies by a number
Would you be able to give an example
That would be infinity
thats a geometric equation
And you wouldn't be able to apply this formula
he didnt ask for an infinite geometric series
The word series implies infinite number of terms
I think it would be helpful for him to unravel the origin of that formula
i asked ai and it said the first bounce is 2/3 of the first drop which is 24 so it would go up 16 and because a bounce is up and down the first bounce is 32
so, we plug it in to the formula

🥀
good for you
bruh
Well, crash course of what a geometric series is:
it's not even correct
!done
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Am i wrong?
Yall aint helping just confusing me thats why i asked ai, but am k right or wrong?
So like is everyone just going to disappear
Destiny said its not correct though
Idk if its the blind leading the blind or what
yes, 120 is correct. although, from backreading, i'm sort of not convinced that you got what the problem is trying to show you.
like for example if i made it so that i want the distance travelled in the ball's first three bounces instead of until it comes to rest, how would you approach that?
Well, i would probably do y= 24(1-2/3^3)/1-2/3 then i think i would times it by 2 cus of the double bounce
sorry, i dont get your notation. do you mean $\frac{24(1-(\frac{2}{3})^3)}{1-\frac{2}{3}}$?
insult
its close. however, the 24 is wrong here. you're basically saying that the first bounce of the object will reach 24 ft, but it doesnt
for posterity, let's try your equation for just the first bounce. following your equation it would $\frac{24(1-(\frac{2}{3})^1)}{1-\frac{2}{3}}=24$, multiplying it by two like you said gives us 48. but that's wrong.
insult
So how do we find this first term?
ill throw the question back to you. how do you think you should find it?
Well i think the first term should be where it starts which is 24 but its prob just the first bounce including both directions
24 is sort of important, yes. however, you need to do something to it first.
here is the diagram above but ive annotated it a little. where do you think i got the 16ft from?
The 2/3 of 24
ok, good. now, how do you think we could get the height reached by the second bounce?
2/3 that
how about the height reached by the next bounce?
2/3
2/3 of what?
Of the previous nimber
would you agree with me if i said that for bounce $n$, the height reached is given by $16(\frac{2}{3})^n$?
insult
e.g. bounce 3 would reach a height 16*(2/3)^3 = 4.74m
Sorry im brushing my teeth gimme a moment
Would you have to account for the distance both ways down and up?
i mean yes, but for now we are only counting the height reached
Ok the height not the distance?
i mean the distance is trivial, since its just twice the height.
Ok so were just doing 16(2/3^3)?
yes, for the sum of three bounces, you could get it from $2(\frac{24(1-(\frac{2}{3})^3)}{1-\frac{2}{3}})+24$. note the two outfront since the ball travels twice the height per bounce, and the initial 24 ft drop height
insult
however, ill continue the derivation for the original problem. notice how for each of these green "bounces", the distance travelled is twice the height, once going up and once going down
thus, if you add up all of these bounces so on and so forth to infinity you'll get the distance travelled for the entire motion
This makes sense
here, ive done some of the heavy lifting in factoring.
do you follow what i did in factoring the equation?
Not really but its fine i understand ehat i need to know thanks for the help
ok. the first part is i factored out the two from each of the terms, and put it outside, the second, i factored out 16, leaving it outside. the two multiply together to give us 32.
the yellow part highlighted should look very familiar to you.
Yea it looks like it does
it should be, because it is an infinite geometric series with ratio r=2/3.
thus, if you write it out, the distance becomes (via $S_\infty = \frac{a}{1-r}$), the distance travelled through all that bouncing is $d = 32(\frac{1}{1-\frac{2}{3}})$.
insult
this should be exactly what ai has given you. then, just add 24 for the initial drop.
Yes thats what it gave me
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Would PL be 110*?
So LNP would be 305 then?
Mhm good
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How many ways can you choose $3$ numbers from the set ${1,2,3,\dots,21}$ such that the three numbers are sides of a non-degenerate triangle?
ihave<skissue>
I assume some ceiling function bs will be involved in it if so.
mm wdym by that
Well, for a non-degenerate triangle, you have that a+b > c for any ordering of sides you choose
Notably, 1,2,3 isnt a valid choice, and you can start counting from 4 to 21, and only considering the choices below those numbers
the bay harbour mathematician?
err what

Is the problem assuming without repetitions?
My idea for it is to fix one of the lenghts, and go about your way finding valid combinations of side lengths lesser than the one you fixed.
yeah
Any pair of sides has a sum larger than the third side
Let a, b, c be the lengths, and wlog, a < b < c, then the only inequality that matters is a+b > c
So we can start by counting triplets st a+b <= c and subtracting them from 21 choose 3
I think you can see it as a sum over c where you choose a and b with a bound over the sum
the answer is in the thousands im p sure, so you would need to do alot of them
actually i just had an idea what if you try recursion?
hmm
My intuition would be in the hundreds rather than thousands, since 21C3 is not that big
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Find the number of positive integers (n \le 100) such that (n \cdot 2^n + 1) is divisible by 3.
Ilikecats
n×2^n+1 is odd if n is odd
it's odd in both cases
odd multiple of 3
now that is clearly
3×odd
= 3×odd= n×2^n+1
now hm what?
That's the work I have done
I can think n×2^n leaves remainder 2 when /3
hi so
Hello
can we replace 2^n by something equivalent when n is for eg even
When n is even it's 2^(2n+1)?
1??
exactly
We take two cases?
yea
since we only care about the remainder, we can take n2^n+1->n+1 (for n even)
This is for n even check cases
for n odd, 2^n gives 2 as remainder
Yeah
so we can replace it with 2n+1
Ohhh
I understand
I solved the problem before but can't put values 😭
Thanks for clearing that
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uhh is (x^2 + y^2)^2= (x^4 + x^4)?
you dont know
im squaring both sides and trying to substitute
in the 2nd eq
lets see if it makes anything easier
1
it does
uh
i think i messed smth up
oh
wait
im getting -1
huh
oh
i forgot its -y/x
oops
yep 1
tysm
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✅ Original question: #help-36 message
new q
how exactly do i complete the identities
because iont think chain rule is the ideal way here
Omar
use $\tan^{-1}\frac{a-b}{1+ab} = \tan^{-1}a - \tan^{-1}b$ to simplify the terms
uh
<@&268886789983436800>
oh so a = 5x and b = x?
yes
crap im dumb
how dint i think of that
umm
we ping mods for that?
<@&268886789983436800>
i got final ans as
5/1+25x^2
does it look correct
nvm its correct
ty
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im lost
Basically i did the equation for the ratio or whateber you call it
r^2=6r-9
you get r^2-6r+9=0 -> (r-3)^2=0 so r=3
but clearly we aren’t dealing with a geometric series of ratio 3 so uh yeah
Idk how to do this
yeah so
it is a repeated root
for a repeated root $r$, the general closed-form solution is always of the form [
u_n = (A+Bn)r^n
]
;(
;(
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✅ Original question: #help-36 message
one more question, part d)
im a lil rusty with group theory so im not sure how i should approach this
i know that a bijection is possible forsure, but idk about the homomorphism part
One way is to identify orders
That is, the order of each matrix needs to match the order of the permutation it maps to
ah
Order being the power n such that aⁿ = e, sry
Oh lol the other questions ask you to find the orders. Sorry I'm slow
Then we also want the order of the permutations
yeah that i forgot
Know how to read the permutations? For example a says that 1 is sent to 2, 2 is sent to 3, 3 is sent to 1
What happens if you do that permutation twice?
you send 2 to 3, 3 to 1 and 1 to 2
and you do it again and you get 3 to 1, 1 to 2 and 2 to 3
so we’re back at e
so the order is 3
This is what happens when you do it once
ou
What we care about is what's actually sent where
I'll let "applying a" be represented with an arrow, and I'll use two arrows to represent applying a two times
1 -> 2 -> 3
2 -> 3 -> 1
3 -> 1 -> 2
That's b. So we have a² = b
so then applying 3 times we get 1 to 1, 2 to 2, 3 to 3 which will be e
k so order of a is 3
Is there a faster way to do this
1 -> 3 -> 2 -> 1
2 -> 1 -> 3 -> 2
3 -> 2 -> 1 -> 3
b is 3
1 -> 1 -> 1
2 -> 3 -> 2
3 -> 2 -> 3
We can do something like:
b³ = a⁶ = e² = e
And that's the lowest power of b that goes to e, since b² = a² ≠ e
Arguments like that can make it a little faster
The order of every element must divide 6, so all orders are 2 and 3 (or 1 for e)
c is 2
But the real fast way is to see how many elements get swapped
i see
cause like in c 1 just maps to itself so it only relies on the permutation of 2 & 3 right
Nd since they map to each other order is 2
Yeye. We call any swap a "transposition"
Well done! That's not enough to find the homomorphism but it helps a lot
Since the order of the matricies need to match the order of the permutations
what else would we need
Can't we use the homomorphism theorem
I did get ahead of myself earlier. We identified a² = b
Is there two matricies, of order 3, such that m1² = m2?
what
Where 2 is 0
What's up?
why is it returning that
Didn't you just do that?
what do you expect it to return
as sets I think
Fuck
Fuck im an idiot 💀
my god i need to multiply it by E again
sigh
,w {{0, 1}, {1, 1}}{{1, 1}, {1, 0}}
E
ok so E is order 2 thank god
wait
ughhhhhhh
i messed up somewhere
A C or D is order 3
ok so B^2=E
Therefore a should correspond to B and b should correspond to E
what about the other ones
That's the right logic! I haven't checked the matricies and am trusting the computation is correct lol
^^ this
We have to distribute the other order 2 matricies to order 2 permutations
We could do something like calculate AB and see what we get
We have free choices here lol
Wait what did we say B was again? Lol
So B maps to b
yes
E maps to a
I'm realizing that both are squares of the other
Of course they are lol. That's the only way you can have two order 3 elements
cd=a it looks like
I = {{1, 0}, {0, 1}}
A = {{0, 1}, {1, 0}}
B = {{1, 1}, {1, 0}}
C = {{1, 1}, {0, 1}}
D = {{1, 0}, {1, 1}}
E = {{0, 1}, {1, 1}}
now you can copy paste for quick calc
thx
,w {{0, 1}, {1, 0}}*{{1, 1}, {0, 1}}
which is E
AC=E
cd=a
so A->c and C->d
whats the last one
we got B->b, E->a, A->c and C->d
D->f i thi k
and thats the isomorphism?
we should sum up everything to check
let's list orders of elements of G
I = {{1, 0}, {0, 1}}
A = {{0, 1}, {1, 0}}
B = {{1, 1}, {1, 0}}
C = {{1, 1}, {0, 1}}
D = {{1, 0}, {1, 1}}
E = {{0, 1}, {1, 1}}
,w {{0, 1}, {1, 1}}^3
B² = E and E² = B. So, we have a free choice here
c, d, f order 2
the cheat code at the end is to check with the group table
p and q are the element of order 3
you can place your 3 elements of order 2 and check you don't have problems
I'm realizing everything is free. Any placement of an order 3 works, any placement of an order 2 works
yeah the placing of order 3 can only be free since it determines after a choice for order 2 too
but you must check the last choice
because pr has to be s
on the table
which doesn't matter much because nobody would write the same element twice ig
Every swapping of elements is an automorphism of S3
But we can't really use that, probably need to prove by construction
you're making a weird statement tho
even tho you can swap the orders two
the automorphism can swap order 3 too
doesn't have to be independent
S3 has 2 generators and then the full table is generated
so you really only have to make two choices
like here ^
Yes. Swapping two transpositions also swaps the order 3 elements
You're right, it's not all free
<@&268886789983436800>
I didn't read all you did before but I suppose you calculated products bc of the idea of leveraging generators
so you could have found the 6 different automorphisms of S3 by making different choices for say, B and A
We started manually multiplying things and seeing what matched to what, but assigning the order 2 elements is a lot smarter
not necessarily because you can use a line from the table
Like, I started with order 3 thinking that would be easier, but order 2 elements are not uniquely defined that way
choosing an element of order 3 fix the other, then you choose the image of a transposition, and there are only two products left
indeed but that's the nice part, you have a choice for order 2 so only two calc to make
I think your way was fine
@lyric obsidian Has your question been resolved?
I mean depends on how much you're sure you have a good iso
we didn't see all your final choices I think?
its up there somewhere
^^
and D->f
i feel like its good
I'll do one quick check
I = {{1, 0}, {0, 1}}
A = {{0, 1}, {1, 0}}
B = {{1, 1}, {1, 0}}
C = {{1, 1}, {0, 1}}
D = {{1, 0}, {1, 1}}
E = {{0, 1}, {1, 1}}
,w {{1, 1}, {1, 0}} * {{0, 1}, {1, 0}}
anyway it's either C->d and D->f or D->c and C->f
so you can check which one is right by calculations (I check, you indeed made a mistake, you chose B->b, E->a, A->c, so BA = C -> bc = f, you can check my calc but seems right to me)
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Translation?
Doesn't exist
thecrumbeler2
wait, should be a some sort of cylinder?
let me refine the drawing
something like this
I would assume this is an application of Stokes theorem
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well there are two methods to solving this obviously first is just using stokes' theorem and the second is just direct parameterization of the curve
thecrumbeler2
so just evaluate each component from there
now that i think about it direct parameterization might be easier
or cleaner at least
you are not explaining why you are using stokes at all you are jumping straight to compute
stokes is a theorem with some conditions
The curve your given is the boundary of an ellipse
its pretty trivial in this case i feel
or not trivial more like its obvious they want you to do this
but if you want i can go through like every step of justifying
but in short the vector field $\mathbf{F}$ is continuously differentiable on $\mathbb{R}^3$, the surface $S$ is smooth, and the boundary curve $C$ is a simple, closed, smooth curve with a correctly matched orientjuation
thecrumbeler2
satisfies the 4 steps
if you were to justify then you would just say since polynomials are infinitely differentiable ($\mathcal{C}^\infty$) everywhere on $\mathbb{R}^3$ and each component of the function ($P = y^2 z$, $Q = x z^2$, $R = x y^2$) is a polynomial (since the vector field is given by $\mathbf{F}(x, y, z) = (P, Q, R) = (y^2 z, x z^2, x y^2)$) cause $\mathbf{F}$ is $\mathcal{C}^1$ on the entirety of $\mathbb{R}^3$, it is continuously differentiable on any of the open neighborhood(s) containing surface $S$ and the boundary curve $C$
thecrumbeler2
and thats for the differentiability of the vector field
next is smoothness and boundary of the surface S and then so on
so like what are you asking here
this is my definition of stokes
how do you know you can apply it
F is C1 yeah
what else
well there are 5 conditions laid out
thecrumbeler2
thecrumbeler2
and as you probably know parameterization is regular if its tangent vectors are linearly independent (meaning their cross product is never zero)
let me show you my definition of regular parametrization
you can prove it many different ways
which i am assuming you can probably do
its not the cleanest but it works
if you can do it then i suggest doing it
are you here?
this fixes the problem we were talking about
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can someone help me with this, ive failed this same assignment 3 years in a row now. its got me in a deep depression lmao. might as well drop out cause clearly this isnt for me
show a screenshot, no one wants to click some dodgy pdf
yeah, could be malware
!img
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@rapid frost Has your question been resolved?
my bad fo real, im sorry
Well u can let equation as cubic
Ax³+bx²+cx+d
Then plug x,y
X,y
Get some equations and solve them
But according to graph
It's not cubic
If u want according to graph
Look
In x€(-2,0)
What's the slope?
how can a cubic give you a piecewise-linear graph?
Well i meant
If u want according to the points only
And not according to graph
U can get cubic
ah i see
@rapid frost Has your question been resolved?
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What is the radius of convergence R of the Taylor series?
The following is a taylor series of a function centered at 8.
power of n
My guess is that the radius of convergence is infinity because we have (-1/7)^n which approaches to 0 as n approaches infinity.
can u guess which test we can apply
does that mean (anything in terms of n) * (-1/7)^n approaches 0?
try ratio test
we can't tackle ^n
no, if I multiply it by something that grows even faster than 7^the limit will blow up to infinity
oh nvm i got it
..close
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Hi guys could someone help me with part b please
i ended up doing this so far
i did substitution so u = root h- 9
idk if the integrals are right, so from 130 - 50
I dont think you need a definite integral
Still no
Once you solve the integral
You'll get a relation ship between h and t
Right?
To get rid of the +C, you know that at t=0, the water height is 200cm
Where is the +C?
All the math teachers are crying
Is C in the lhs or rhs?
i mean does it matter cuz i integrated both? but I put it on the rhs
where t is
but is it better to put it on the lhs so then c could be positive
C does matter. But if you put it on the rhs its fine then
sorry not if c matters, but rather the side?
Doesn't really matter as we are nearly finished with the question
like it could be lhs or rhs
okayyy nice thank you so much
so then after i input 50 for h?
Yes
omg ur so smart
same answer
so how did you know not to put definite integral?
cuz the mark scheme said that but i guess this way is easier to know
Think of it like this. If C is on the lhs, you'll get 1 value for C. If its on the rhs, you'll get another value for C. But at the end of the day both values solve the question
okay fair enough, love that
Not really. There are so many people smarter than me
u areeee, take the compliment 🥰 , alright i got the answer thanks to you!
Because there is no need to. The question asked for a value of t when h=50, indicating a relationship between h and t. A definite integral wouldnt give us that relationship
Thank you ❤️
fair enough the mark scheme was giving all sort of bs
ok nicee ! Thank you again
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Who makes ts
No problem
No one can read that. It genuinely looks like a mess
But wait
Defenite integrals is possible
Like they did in the solution
Do you want me to explain how @mint forum ?
Literallyy its so useless like it overstimulates me reading that shit
Yes please 😭
Sorry for wasting your time
Reopen the channel first
I have quite a bit of time. Your not wasting any
.reopen
✅ Original question: #help-36 message
So basically
Yay
A definite integral is literally a fancy way to solve this question
Because the 2 integral were equal
Okayyy
If you were to integrate them both from points that both the values are equal at, then you'll get the same value
Why was the 50 at the top compared to 200
<@&268886789983436800>
Okayy nice
0
So if integrate h from 200 to 50, then you can integrate t from 0 to T
Idk how to work around that
But you'd still get the same answer if it was the other way around
so 200 at the top and for t , 0
Okayyy so thats fine then
But you'll have to change the other one too
Liek if you integrate form 50 to 200, you'll integrate t from T to 0
Thank you for explaining that
Yess, amazing!
Sorry I have one more question
But let me finish doing it first 😭
Do say
Lowkey thought I opened a channel
Similar name to you so its understandable
i'm crying 🤣
hi twin
okay with part b
i've done this so far
excuse the handwriting, litch writing with a mouse
idk how to get it into that form
Helo
The second part seems a bit wrong
Give a minute ill try solving it
Yes your second part is wrong
You dont get $1/P +P-2$
-TimeLord-
Could you maybe show your working?
I would highly reccomend you write this on a piece of paper
But ur so close
The on with the natural logs in it is correct
But how do you do the step after it
okayy thank you
so then i multiplied it all by e
to get rid of the ln
then it gave (p)^-1 + (p-2)
= e^1/2sin2t + c
Just wait
$ (p)^-1 + (p-2)
= e^1/2sin2t + c $
ugh i cant make it into ur format like this
okayyy thanksss
Im still confused on how you solved it after
-TimeLord-
After this hope for you solve it
okay thank you lemme try
Wait. You do realise that if $f(x)+g(x)=h(x)$, then $e^{f(x)} + e^{g(x)} \neq e^{h(x)}$. And instead $e^{f(x)+g(x)}=e{h(x)}$
-TimeLord-
Basically if you do e raced to the power of both sides, then you have to do it for BOTH SIDES and not each ELEMENT?
yes im aware thank you, I got the answer 😭 i appreciate u so much for ur help
I shouldn't of done e so soon but i ended up getting it right thanks to uuu , again
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stuck on this problem for some hours now can't seem to find the next step
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✅ Original question: #help-36 message
Just to check is this correct?
The derivation in your notes contains a fundamental error in the section where the p should be equal to one
@summer yew Has your question been resolved?
Where?
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✅ Original question: #help-36 message
@summer yew Has your question been resolved?
Since you use Cauchy Schwartz then he’s implying that p=+-1
yeah I've done it in my corrections
so that's it? I've cleaned everything up
Yes
When p=0 it assumes and assume a deterministic linear relation it becomes inconsistent with the rest
When p=-+1 it becomes consistent
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thank you so much! i can go see my family now
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How is it possible to have (a_n)(x_n) terms? Are (a_n)(x_n) terms just theoretical?
a_n is a sequence, x_n is a coordinate
so, say x_n from n = 1 to n = 3 is a """sequence""" (x,y,z)
and a_n from n = 1 to n = 3 is a sequence (3,7,2)
They are any and different variables
In here, the linear equation would be
3x + 7y + 2z = B
If my understanding is correct, then that just refers to how many terms and coefficients of those terms there are?
that's what the n means?
It has to do with the space the elements of the solution set reside in
Tysm! I thought that this could just happen infinitely, and that maybe for a given equation there's just an invisible a_n xn or something where they just equal 0
Say, in the example i gave, the solutions are vectors in R^3
yea, the coefficient can be 0
Anything that answers the solution forms a plane in this equation?
And if you want you can sometimes extend to n -> infty
Infinite dimensions/terms?
generally if we write ... + a_n x_n, we're stopping at an n-th term so it's going to be finite. but if we want to represent an infinite number of terms, we would write a_1 x_1 + a_2 x_2 + ... , without adding a "last term"
As a learner of this book, do I have to completely understand all of that perfectly before moving on?
The concept of plane is a bit arbitrary, since in reality it depends on which dimension youre working on
So 2x+4y=3 can be considered a plane kinda?
say, Ax = B is a point
Ax+By = C is a line
Ax+By+Cz = D is a plane
that's what i'm most familiar with
Ah ok!
What about x_infinity?
is that also a thing?
I believe I understand it now! the term after the ... in the image I showed is just the last term in the equation you're looking at?
Yea, at that point you usually are working from a purely symbolic standpoint relating to lin. algebra
And the equation has to take the form of that to be considered in standard form of a linear equation?
Thanks!
I really appreciate clearing it up!
Here x_n is also just the last term that is defined/exists?
Thanks for the help! I'm pretty sure I understand it
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yea
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Did you like even read the problem?
yeah
It would be nice if you attempted something.
well green is out of the question, so either Stokes or Gauss, but since the region is I believe in R3 we would be prolly needing gauss for this one
other than that, I was trying to understand the geometric intuition on the region S, seems like a disk intersecting with a plane
It's a solild cylinder intersecting the graph of the function 2 + f(x,y).
So you can imagine taking the graph z= 2+ f(x,y) and keeping just the part that's above the disk x^2+y^2 <=1 in the xy plane.
You do have the information that f(x,y) >=0 and that f(x,y) = 1 on the boundary
hello 
care to elaborate?
That’s just what it means to intersect the graph z=2+f(x,y) and a solid cylinder
however we dont know what f(x,y) even is dawg
Id swear you can actually use green if youre crazy enough, lmao.
But you’re given info about what it looks like on the boundary
the vector field is of R3
Ill spoil you into it, you have to use stokes
And it happens to be that you can find the intersection pretty easy by the definition they gave you of f(x,y)
I need more help and avoid giving out spoilers because I prefer hints
@glossy zephyr @blissful meadow @drowsy epoch
Whats the value of f(x,y) at the boundary of the cylinder
the other lad said stokes tho
@glossy zephyr @blissful meadow
what are we using gauss or stokes dawg?
z = 3
The issue with Stoke's is you'd need to find G such that curl G = F.
So you have a surface which bound is a constant circle (because its the intersection of a plane and a cylinder) at z = 3
Stokes takes in the curl of a vector field in the integrand. Seeing as F is given as the integrand, you need that integrand to be expressed as the curl of some vector field, no?
The main idea is that because f(x,y) >= 0 and f(x,y) = 1 for x^2 + y^2 = 1, then you know that S touches the plane z=3 on the outside (x^2 + y^2 = 1) and it has to bulge upwards in some way within x^2 + y^2 < 1 because f(x,y) >= 0.
To use the Divergence Theorem, you would need a closed surface (like we did in the past. you need it to enclose a solid 3D region). What simple shape could you stick to it in order to close it up?
z = 2
either x^2 + y^2 = 1 or z = 2
well this shit isnt about guessing
Oh, mb, get what you mean, still, i think stokes turns out to be easier since closing the surface takes a few steps.
Its pretty easy to find G
Oh okay I thought it was hard at first. May be simpler than I thought.
Divergence is just nice because ||div F = 0|| I guess
yea ||div(curl(G)) = 0||
Indeed
i need help
There are two ways to do it.
You can use Divergence Theorem (Gauss) and struggle with calculating the Flux Integrals of the non-meaningful parts of the solid.
Or you can use Stokes Theorem and struggle finding the Vector Potential for F.
Id advice you go with the second, but you can do it however you like
@gentle zephyr Has your question been resolved?
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basically you take the x and factor it
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no problem happy to help
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24th problem, Idk how to factorise this equation and I think that maybe graphing will help but I'm not allowed for that.
Ping me if yk what to do here pls.
@patent compass you might want to draw out a diagram and maybe solve it by proportions
proportions?
wdym
like with the ratios given you can find AP/PD
Sry but I struggled on 24th
not 23.
I shouldve cropped that part out mb
@patent compass Has your question been resolved?
Hint: The left hand side is usually bounded between which two perfect squares?
Oh also idt factoring is super fruitful here
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How do we start such problems?
take three arbitrary elements of P(S) and check if they satisfy transitivity
your approach will be a bit different based on whether it's actually transitive or not
this is required if the relation is transitive, but otherwise you get to choose 3 specific elements and show that they don't satisfy transitivity because you just need a single counterexample
in this case the relation is actually not transitive, so you need to find three sets A B C where A ⊄ B and B ⊄ C are true but A ⊄ C is false
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✅ Original question: #help-36 message
if I take power set as {(1),(2),(3),(12)(13)(23)(123) phi}
A-->(1,2)
B-->(23)
Clearly A is not subset of B
C-->(1,2)(1,2,3)
B Is not subset of C
But A is subset of C
wdym phi?
empty set i assume
is C (1,2) or (1,2,3)
it can't be {(1,2),(1,2,3)} because that's not an element of the power set, that's a subset of the power set
Hey man, are you doing an intro to math course?
Yeah...new in math cord
If we take c-->(1,2)
B is not subset of C but A is subset of C...but they should make the subset sign more convenient because it seems proper subset@novel kettle
yeah that works
oh wait proper subset
hmm
might as well take A = (1), B = (2), C = (1, 3) to be safe
perhaps, but shouldnt the proof be for all possible combinations? i'm sorry im doing a foundations to maths course too
soo addressing this to other experts here :D.
it's a disproof so you only need one counterexample to show that it's not transitive

