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The 1st line in yellow after Let (x,y,) be the foot of the perpendicular is the formula
okai so how am i supposed to apply this 
Do you not know the standard form of a line?
i know nothing man i am doing from scratch
Standard equation of a 3d line is ((x-x1)/a)=((y-y1)/b)=((z-z1)/c)
Compare points here with the form and substitute in the above formula
alr alr let me see if i get the answer
solved with system of linear equations
linear like the highest exponential degree present is 1
0.12b = 0.10a + 1400 ; linear
0.12b^2 = 0.10a^3 + 1400 ; not linear, is cubic, highest degree is 3
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What have you tried
I have tried like 14.5 - 6/9 but I don’t think that makes sense 😭😭
What is your reasoning for doing 6/9?
Honestly I don’t know😭 originally I was thinking of doing this:
But I just had an exam and I honestly cannot think straight at all
Okay
Hey guys
start by computing the total marks from all the exams
then remove the mark from the one to be revised fromn the total
compute the mean of the remaining ones, remembering that there's one less exam for the new total mark
What she has done is also correct.
this one? that would assume that the mean doesnt change, which it does
Is the new mean 14.8
? No?
Yes!
Or unrounded is 14.8667
Yep
She's taken new mean as x
Thank you for the help!
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for 3cii, so far i've said that p3 and p2 intersect as because they are non-parallel, they have to intersect. is this correct?
or can you also argue that it depends where p3 is positioned because it could be small enough that it doesn't touch p2
im just finding trouble with drawing c ii)
yes it is correct
any plane parallel to P1 will be nonparallel to P2 and so intersect it
how do you represent that visually?
this sort of idea?
welp
oh
each of the 3 lines in there becomes a place
ish
wait how do i draw it so it looks acceptable to write up
eh. good enough for me tbh
yeah
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How is example 1 not transitive?
missing brackets but correct points
Yes sorry about that
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Thanks
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so i hav to find the bounds for the triple integrals of the following function
z^2+x^2+y^2=9
bounded by the cone z=root(x^2+y^2)
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@vital blaze Has your question been resolved?
Have you tried cylindrical coordinates?
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can someone explain this in normal english please
does that not mean that the lowest heart rate before is 52 😭 ?
Uh
This doesn't look right at all
wym
most cursed stem and leaf I've ever seen
It's not formatted correctly
@wispy jay Has your question been resolved?
@wispy jay Has your question been resolved?
@wispy jay Has your question been resolved?
@wispy jay Has your question been resolved?
R u sure u have the right paper cuz there should be numbers in the fitness after the programme🤔
@wispy jay Has your question been resolved?
i figured it out
for the first row of values notice the middle 5 has values increasing on either side
meaning that's the number in the stem
beyond that just place each next number (6, 7, 8...) in the stem and properly format it
wait what the hell is that 4
oh gosh
oh the 4 probably belonds to the first row
this is all speculation
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Question says calculate derivative of x^a*y^b=(x+y)^(a+b), now, I don't really know a method to do a 2 variable derivative, the answer is y/x but I want to know how to reach it, it doesn't seem I can use any of my known methods to reach an answer.
implicit differentiation, i.e the chain rule
so $\frac{d}{dx} (y^b) = by^{b - 1} \cdot \frac{dy}{dx}$, due to the chain rule
south
y is a function of x
So it would be axby'y=(a+b)(x+y)(x'+y')?
slow down
(cause that's completely wrong)
you need to use the product rule first on $x^a y^b$
south
oh you mean u*v?
so that would be $x^a \frac{d}{dx} (y^b) + \frac{d}{dx} (x^a) (y^b)$
south
that's what I mean yes
If you don't mind me asking how did you separate (x+y)^(a+b)?
I didn't talk about that part yet
Ok so you just did the left side of the equation right? We are missing (x+y) then
yes
okay now for the right hand side
you have $(a + b)(x + y)^{a + b - 1} \cdot \frac{d}{dx} (x + y)$
south
also remember that d/dx (y) is just dy/dx
So if I am understanding this correctly
for the left side you did dy/dx uv = uv' + vu'
And for right side you did u^n=n*u^n-1 u'?
not what is asked but u can also just put a=1 and b=-1 and get the answer directly
you'll need to do that anyways since the options dont include a and b
maybe thats the method they wanted you to use (incase implicit differentiation isnt taught, which will also include putting values of a and b in this case, but after the differentiation, as opposed to putting at start)
I mean if it gives the correct answer who am I to judge, but wouldn't it give x/y=1? Or am I doing something wrong?
x/y = 1 is the simplification of the original equation
you're yet to differentiate it
it asked you to find dy/dx
yeah like if it's multiple choice don't bother doing it the proper way
MCQs don't actually teach maths in my opinion
they teach how to guess correctly
the a=1 and b=-1 step will have to be done regardless
So which would be the strat? Try to equal a side to 0 exponent?
but yeah u can just put at start instead of after the implicit differentiation
makes it easier in mcqs
really? how?
you still have a and b in your differentiated equation
what do you do about them
I mean the assumption is that dy/dx is constant regardless of what a and b are
Sorry for asking this question but how do you differenciate x/y=1? It has 2 variables I don't know sorry 😔
x = y, or y = x
so dy/dx = 1..... yeah unfortunately it doesn't work
chain rule
well
I mean 1 = y/x here
but so is x/y = 1
so you've eliminated options A and B
you can't tell C and D apart
yeah but you have to get rid of them, no?
How did you guess we could just do a=1 and b=-1 by the way?
to simplify and reach y/x
not guess
experience with MCQs
the equation given is x^ay^b = (x+y)^(a+b)
put x=y=1
1^a1^b = (2)^(a+b)
1 = 2^(a+b)
for this to be equal
a+b = 0
so a=1 and b=-1
Woah, then after doing that and getting x/y=1 how do i implicit differenciate?
d/dx (x/y)
you know division rule right
(y.1 - x.(dy/dx))/y^2 = 0
the dy/dx comes from implicit differentiation
You mean u/v=uv'-vu'/v^2? division rule?
Aight
Thx got it
i forgot how to use latex so
now just solve for dy/dx
y/x=dy/dx?
I wrote it wrong 😔
lol, yeah its correct now
Kinda cool problem, got anything else like this to try and refine my skills? Thx anyways
solve actual questions
Understood, by the way what if we did a=-1? is that wrong or would we still achieve the answer?
if a = -1 then b = 1
because a+b = 0
if u put both -1 then you wouldnt reach anywhere since a and b still remain in the equation
Would that affect the answer or would it still be fine if we did a=1 b=-1 or a=-1 and b=1?
the only reason we eliminated a and b is because there were no a and b in the options
both are fine
Oh I see, thanks for the MCQ hack
Except 0?
Not really
I got the answer without doing that
Ok
how
Just do an implicit differentiation
It's not thay hard
The a and b terms cancel out

sub in $\left(x+y\right)^{\left(a+b-1\right)} = \frac{\left(x^{a}y^{b}\right)}{\left(x+y\right)}$ then keep cancelling and then expand a bit later
south
Yep
But if this an mcq
And it was an exam
I would probably put a=1 and b=1 as well
Or some other value to make it simple
I'd agree that mcqs don't help in progressing math skills, they only help in making you quick
agreed
Is this always applicable?
In this case yes
Where would it not be applicable?
Where the relation is not given?
it comes from $x^a y^b = (x + y)^{a + b}$ so yes
south
what I did holds for any x, y, a, b
well bx - ay can't be 0 but that's the only exception
Oh I understand it now
Was also a bit skeptical since this term came in both RHS and LHS While differentiating
You mean while?
Ye
Then what would the process be? Do I do derivative u/v then?
Well I'll research it myself, thx for the time
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Question A(9,a) and D are on a line l1 : hx - 4y + 3 = 0 and B which is 6 units away from A is on a another one l2 : 3hx - 4y + 9 = 0,both line intersect at C
Show that a=3 and h=1
I tried this question a few times and can't solve it, idk if its a flaw in the question or it is my issue cus even if I got the question wrong, my answer is inconsistent
@alpine sable Has your question been resolved?
im inclined to call xy
there's information missing
was there a graph or something we can go off of
!xy
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.
Oh yeah there was actually
Sorry the graph was kinda sketched really small on my hand when my friend gave me the peroblem but here is what the graph looks like
He had his exams awhile ago and he asked me if i could solve that question
I feel like there is missing info but im not sure
lemme see if relating B and D in some ways gives this result
because as of right now the problem is either over or under determined
How would you relate them though
im seeing whether they have the same x coordinate or if theyre perpendicular or what, and i'll assume the question gave that info
The question has a few parts so i believe B C and D are just cordinates for the other parts
because the question you stated has insufficient relationships
I see
I see
My friend may have just forgotten
But still cant explain how i got my answers inconsistent
I got 4a=9h+3 for substituting A into line 1
Then i solved the gradient of line one using point A and the y intercept
Which i got 4
from a purely graphical standpoint USING the values given by the question to get the graph, we see that the question probably tells you that the x coordinate of A and B are the same
Its wrong but when i did the same thing using pythogoras and point B with line 2
And got
4 answers which is scary
Ooo
however B could be either one of the points that intersects the purple line
we just know it's 6 units away
but judging from the nature of the question
it's a fair assumption
It could be the second iwrsection tho
Yes
I see
yeah i think that's the missing puzzle piece
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Oh icic tq
Yes i know
Thanks
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if ur done ofc||
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well technically helpful (green) roles can too but i feel it's kinda rude to close someone else's ticket
Ohh icic tq tho XF
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i can't figure out what these symbols mean
you mean $\circ$ ?
Denascite
composition
well without context we will not be able to do anything either
if you click on it you will see the rest
it should be on there.
a translation would also be good
but T, omega, S seem to be some sort of geometric operations
that notation is explained somewhere earlier in the book most likely
i basically dont understand anything its trying to say my teacher did say it was written in an unorthodox manner but like
i really dont get what it wants
what are they even supposed to represent 😭
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I think i might be bugging but how do u integrate a function like this by recognition
1/(x^2+16)^3/2 ?
Ye
Put x = 4 tan theta
U cant do it by recognition?
Wdym by recognition
Some tough paper i got lmao i aint got time to do a usub
Reverse chain rule
Or like yk how u are familiar with a integral
Urs will lead to a answer but it will take
Abit of time
Tbey jumped the step
I'm very familiar with 1/(x^2+a^2)^3/2
So i do x = a tan theta
Why memorise when you can do it just as easily
Time pressure
It really doesn't take that much time
That's the full q
I need to do it in 12mins which may sound alot but idk now i think abt it i got plenty of time but when ur stuck
And then u need to do it qucik
Longday maj
Man
It's literally just integral cos theta after substitution..
Also not really memorising tbf ur method is probably the way to go
I get some formulae ij my formula booklet
I see them do it in one step
So i thought i should be able to do it
That's cuz they've probably done the rough work somewhere else before writing it
Can you help me with another q btw im kind of confused
Wouldn't really be a formula sheet if it contained 3-4 formula on one page
ha decay
Part d and e but lets even starttof with a b c
While we are at it
Q1, u can write both as modulus argument /polar form
what
Yep
Argument is not unique
Yes
Then apply demovirws theorem and u get three roots
B is simple
C ie also simple ngl
D and e is where im confused
That's my solution so far brw
Hmm
The e^itheta term will remain the same
Only instead of beta it will become beta^(1/3)
Problem solving ig
I know
There's still no mention of alpha being equalto z0 anywehre
When you drew the diagram for a and b part, what is the triangle y9u got
Eqyalateral
Equailatetal
Equalateral
Yh icl idk the spelling
But we move
Equilateral
So now shift the origin to the point z0
Ah its kind of like a graph transformation
Ive always never been happy with those is there a strong idea on why f(x-2) shfits to right without just considering the graph
Itself
Liek ik it does that just from considering tje graph
The idea is transformation in itself
Wdym
Idk how to explain, ig you could just plot some points to observ
Yh ik that
Tjwts hwo i know it
Tbf Just considering tje input would work aswell
Ig
Yeah
You know vietas right?
Yes
Yh ik that
But theres a way to go about it with graph transformations
Esp the second one
Intriguing
That's not really transformation of graph, it's transformation of roots
And that's going to be lengthy to do
No here y9u aren't shifting the graph of anything
The graphs are entirely different
Ah but the roots are changing
I mean i stil feel like it is some sort of transformation
Of roots
Sure
Actually what we did earlier can't be called transformation
It's more so translation0
Thats a type of transformation
Like changing our reference
Not really cuz here everything else remains same except for our reference
The roots are changing and the graph itself will definitely change
When you transform roots, you're changing the Vertex, length of latus rectum, curvature of the parabola
The worst bit is i understand vaguely what yojr saying 😭
Ur complicating it
Nog even vaguely just understand it
I just understand
Anyway thanks
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????
Bro said latus rectum
If i didnf watch some niche video on it i would never of understood
But mabye u had high hopes for me 😂
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Hello 🙂 I am struggling to understand why they can just dot product the 'end points' of each line in their solutions to this question (I underlined in green). I would assume, that to see where the paramaterised lines are orthogonal, you need to take into account the initial points of each line because this together with the end points determines the directions of the lines?
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could someone explain how this formula works
$u^v = e^{v\ln u}$
rafilou is not not born in 2003
so chain rule with exp says $\frac{d}{dx}(e^{v\ln u}) = e^{v\ln u}\frac{d}{dx}(v\ln u)$
rafilou is not not born in 2003
meaning $\frac{d}{dx}(u^v) = u^v\frac{d}{dx}(v\ln u)$
rafilou is not not born in 2003
and now product rule + chain rule (for derivative of ln(u))
how does $u^v = e^{v\ln u}$
Nox
is there a property or rule that I am missing
I understand the rest of your explanation
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I have one question about LDA
!da2a
No need to ask “Can I ask…?” or “Does anyone know about…?”—it’s faster for everyone if you just ask your question! See https://dontasktoask.com/
Linear discriminant analysis
This is the plot of the scores
Basically i am trying to distinguish the beens of coffe of free different colors
But at least in my opinion there isnt a clear separation of groups
i
And each group is normally distrivuted and the variance and covariance is equal for the three groups
And the Linear discriminant functions are statistically significant
So this shouldnt happen right ?
@vestal shell Has your question been resolved?
@vestal shell Has your question been resolved?
@vestal shell Has your question been resolved?
@vestal shell Has your question been resolved?
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@vestal shell Has your question been resolved?
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how did my teacher get this??
how are you getting pi/3
on the unit circle they're equivalent right?
like for their exact value table
tan is positive in the first quadrant, and negative in the fourth quadrant 
yea i get that part
what calculations are you doing to get the value of pi/3
and tan(11pi/6) is not equivalent to tan(pi/3) in absolute value
well its 2pi/6
what calculations are you doing to get the value of 2pi/6
on the unit circle they like follow the same line
wait lemme get a diagram
aren't these all equivalent?
in their cos and sin value?
oh so is it equivalent to pi/6?
oh yeah
and since tan is negative in Q4, the result
= -tan(that reference angle)
yup
how does he get -1/2 though?
tan for pi/6 is root2/3
so wouldn't it be -root2/3?
oh
tan(pi/6) would be 1/sqrt(3)
or sqrt(3)/3
yes.
okay, thank you so much :D
and thanks for ur patience sorry haha
im not running on much sleep

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is there a function to approximate how many valid formulas in the first n godel numbers?
thanks in advance:3
by valid i mean well-formed, not correct
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@twilit dome Has your question been resolved?
what encoding are you using?
sorry, i thought there was only one?
based on prime factorisation?
but either way, being approximated by a computable function is a fundamental property that can not change throughout different encodings no?
@dire plover
In mathematical logic, a Gödel numbering is a function that assigns to each symbol and well-formed formula of some formal language a unique natural number, called its Gödel number. Kurt Gödel developed the concept for the proof of his incompleteness theorems.: 173–198
A Gödel numbering can be interpreted as an encoding in which a numb...
yes, there is such a formula, i thought you were asking for the formula
what is it
depends on the encoding, but anyway, checking whether something is well formed is doable(i mean we have algorithms for this which will always halt), so we can just go over all godel numbers till N check whether each one is corresponding to well formed formula, and adding them up
sorry, i meant to phrase it clearer, i meant that is there a function to approximate that number, like defined by operations. for example log log x
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Which answer form is equal to my answer
From the options?
Why option A is not correct since it includes 1 and excludes 1 and 4
Looks like Set Difference Notation. The subtraction sign indicates that 1 is excluded from the interval on the left.
your answer is equal to (-1, 4) - {1}
you mean "excludes -1 and 4". do not drop minus signs.
Is (-1,4) - {1} equivalent to x belongs to (-1,1) union (1,4)?
erase the words "x belongs to", then yes.
you can say either of two things:
\begin{enumerate}
\item $x \in (-1,4)-{1}$ is equivalent to $x \in (-1,1) \cup (1,4)$
\item $(-1,4)-{1}$ is equivalent(/equal) to $(-1,1)\cup (1,4)$
\end{enumerate}
either write $x$ in both or drop $x$ in both but don't mix
Ann
did you mean this as a statement ("The concept isn't clear to me.") or as a question ("Bruh, is the concept not clear to you anyway?")?
To me
ok, then let me tell you: there is no concept. it is only a style thing.
I want to learn this trick
what trick?
Style
style is not a trick
Actually the format
your answer is equal to (-1, 4) - {1}
i already told you this earlier
we can repeat this 20 more times though if you want
your answer $(-1,1) \cup (1,4)$ is equal to $(-1,4) - {1}$, which is option C.
Ann
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i need help on this question, why dont they use positive value of cos0
Cos can be negative
oh wait
ok
They want BC to be longest right
yes
if the cosine is positive then BC is not the longest
ah okay thank u so much:D
becos cosine is negative when the angle is obtuse, then BC is the longest side of the obtuse
np
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If I have a polynomial of degree 2 which attains the value a at x1 and another polynomial of degree 2 which attains the value a at x1, can we show somehow that they have the same derivative b at x1?
nope.
too late. you can only reopen before your channel releases. you need to get a new one now.
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I somehow want to show that a basis spline of degree 2 has equal derivatives at the knot
do i have to open a new channel? hahah
mmm might need some more details for that
do you have a formula for the splines you're working with
i think i want to show this relation:
If a knot has multiplicity miu, then the continuity there is C^(degree - miu)
i.e. this
though I am not sure how exactly you can see it
https://pages.mtu.edu/~shene/COURSES/cs3621/NOTES/spline/bspline-property.html this formula (Cox and de Boor)
@verbal gyro Has your question been resolved?
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@verbal gyro Has your question been resolved?
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anyone know where i went wrong here?
question was: In triangle ABD, AC = CD = CB. Let vector AC = u and vector BC = v. Use vector method to prove that angleBAD is a right angle
doesn't seem so, its the solution 🤔
only the white one though, idk what's being written in green (wrong)
@leaden fiber Has your question been resolved?
wait
i meant
isnt
vec CB = - vec BC
so like since BC is v right? then CB is also -v?
Yes
So like, vec CB = -v because BC = v
is that wrong?
Idk ig my thought process was a little convoluted
Direction matters
Same magnitude doesn’t mean they’re the same vector
Yeah that makes sense
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i dont get why they used 4th one for lagrange in part (c)
Are you asking why they have f^(4)(c)? Or am I misunderstanding?
maths and physics is so nice
yea im lowkey confused why they used 4 for n+1 and the terms
i like both
P(x) is a third degree polynomial so u use 4th degree for the error bound
but where did the (1/10)^4 come from?
Do you know the formula for the Lagrange error bound?
partially, yes.
idk where they getting that
The lagrange error bound has the form $\frac{f^{(n+1)}(c)}{(n+1)!}|x-c|^{(n+1)}$
Spuerst
yea
|x-c| = |1/10|
where does that number come from
the question itself.
if you compare this to the sheet, can you see how they get $|f^{(4)}(c)|\left(\frac{1}{4!}\right)\left(\frac{1}{10}\right)^2$ ? by plugging in the numbers you know and are given?
dawg 😭 so i js straight up use that?
Spuerst
yea
oops, made a mistake in the latex. should be (1/10)^4, not (1/10)^2.
why does mine look same
but we want to exaggerate the error anyway
i got it from that site too i think lol
yes.
where do they got max f value? do i js plug in to get it
ok so
fourth derivative is 5^4 sin(x), right?
max of sin(x) is 1
so max of that is 5^4
yea
,calc 5^4
Result:
625
oh i get it
so the method is find max f and use the 1/10 they give and set 1/4!
1/10 = |x-a| right
1/4! = 1/(n+1)!
yes
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Don't know how to start
ok so im just gonna paste the problem with the diagram as only one image so as to not let discord cropping get in the way of readability:
In how many ways can we color the points E-J in the figure below, each with exactly one color, if we have red, green and blue available and must not allow any three collinear points to receive the same color?
@upbeat pilot are you familiar with the inclusion-exclusion principle
Thank you
No
sad
Should I be?
if i may
well, i was going to suggest a route with it.
isnt there a rlly easy way to do it?
||these||
||w.l.o.g let F be blue. this forces IJ and GH to be red and green. this forces E to be blue. IJGH are either red blue blue red or blue red red blue. then just multiply by three for all maps from (1, 2, 3) to itself with no fixed points|| <---- full answer
hint: consider the implications of fixing point F
I only looked at that for all of 2 seconds, but are you assuming that all three colinear points must be different colors.
yep, thats part of the problem statement lol
.
Can you explain that, please
ok
whats your fav colour
out of red green blue
pick any, it doesnt matter which one u choose
yellow
hooold on.
I interpret the problem that if you have three points on a line, they can't all simultaneously be the same color, not that they must be colored RGB
AH
If you fix F to be a color and make that assumption, you don't need to do any math to know that the options are combinatorically impossible
oh that makes it a bit more complicated then my bad
how so?
Yes
it doesnt lead to any contradictions
Those numbers are huge and I expect your answer with those assumptions to be small
(A) 279, (B) 324, (C) 405, (D) 450, (E) 648
These are the options
Guys, I think I have and idea. I know that for the lines HJE and HGF are 108 legal ways to color
Like, H is red, if J is red, there are 2 colors for E, if J is blue, are 3 colors for E and if J is green there are 3 colors for E, so there are 2 * 3 * 3 = 18 ways to do it
The same thing happens to HGF, so 18 * 2 = 36. H can be any color, so 36 * 3 = 108
Now I have simply to discover I possible colors, right?
<@&286206848099549185>
but thats not an option
wdym
108 is not an option in the question you sent back there
Indeed, that is why I have still to discover I possible colors
I am dumb, I shouldn't have multiplied lol
So the total possible colors for HJE is actually 24 because there are 3^3 - 3
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hey guys learning gtraph theory rn. so i get the gist of it; like lets say k = 2. just chooose some arbitrary vertex v1 and that vertex v1 is connected to two other vertices: v2 and someone else. then v2 is connected to v1 and some otyher vetex v3. but im not sure how to turn this into a rigorous proof. could i get a small hint?
@rose hinge Has your question been resolved?
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let P be the longest path in G, and use the maximality of P
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how to prove that this angle is $\alpha$
<rajel />
\begin{align*}
&\text{we are given a circle and given that} \ \
&\alpha = \left(\vec{v'}, \vec{v_0}\right)
\end{align*}
<rajel />
How do you do that
do what
Latex formulas
you can do it with just the blue parts i think?
ask in #latex-help
interesting step
so the right triangle can help ?
assuming those angles are all right angles this should be pretty straightforward
yep they all right angles , but i still cant see it lol
,, \frac{\pi}{2} - \alpha
<rajel />
sure yeah
the thing is how would i relate it to the one in the left
then examine the kite-looking quadrilateral on the left
i see it now thx
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is that the same as (f^-1)'(a) = 1/f'(f^-1(a))?
yes because x_0 = f^-1(y_0)
so how would I use this rule to Find (f^-1)'(3) when f(x) = x^3 + x +1?
I guess y0 = 3
so 3 = f(x)
yep
okay so I need derivative ig
3x^2 + 1
then just plug in?
okay so you get 4
we know f’(1)=4
so is the answer just 1/4?
betttttttt
thanks so much!
you’re welcome
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the emoji spam bro
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why is the solution of a non homogeneous linear recurrence relation the sum of the general solution of the associated homogeneous relation and a particular solution of the non homogeneous relation? This seems very similar to how non-homogeneous solutions of a linear system are just displacements of the kernel, but I can't make the connection and it's driving me crazy
Have you seen https://youtu.be/TXg0lajMdn4
Group theory arises throughout mathematics, but this is not at all clear to someone learning it for the first time. Many of the applications, are in areas such as number theory, combinatorics, geometry, and topology, which are more advanced and typically learned later. In this lecture, we’ll see some of the basic theory of homomorphisms that w...
I haven’t, from a first skim it seems to talk about ODEs which I have seen compared often to recurrence relations. But I’m not familiar at all with differential equations and their solutions yet
It’s more about what’s similar in different areas of math
And your linear algebra example is one of the examples
I have studied group theory so I’m familiar with the concept of isomorphisms and homomorphisms. In fact I suspect there must be some such relationship btw linear systems and linear recurrence relations
The video showcases the reason why this is the case for linear systems, which Im familiar with from group theory and the first isomorphism theorem, but I don’t know the homomorphism that would let me apply this same lens to linear recurrence relations
The ODEs can also be solved by linear recurrence relations , just by trying power series solutions
That’s one way of getting your link
I wish. Apparently the annihilator method and such are quite linked to this, but since I’m completely unaware of ODEs and their theory that approach is a bit too much for me atm
Keep it in mind for later 🙂
I will, and surely when I study ODEs I will come back to this and understand better. But rn I was asking for help from a viewpoint I could understand, which includes linear algebra, group theory and, if necessary, up to calc 3
Ok, this is as far as I go. Good luck!
Thanks for your time regardless
@tacit sierra Has your question been resolved?
@tacit sierra Has your question been resolved?
a
that is true! i had this thought:
one may think of the following "linear operators" on sequences:
$\phi_{i}(a_k) = a_{k+i}$ for every integer $i$. Then A system of recurrences may be seen just the way you see systems of linear equations
fastrack_and_backtrack
if you have studied differential equation theory, it may ring a few bells too
Unfortunately I haven't. But I've devised the following, if you would care to see if it makes sense to you
it's similar to what you pointed out here
i have no problems in seeing 😄
hi yall
let $$ a_n = c_1a_{n-1}+c_2a_{n-2}+p(n) $$ be a non-homogeneous recurrence relation:
let h be the general solution to the associated homogeneous relation
let s be a particular solution of the relation.
If we claim any solution has the form h+s, then we could surmise that h must be the kernel of some homomorphism P by the 1st Iso thm
Hold up ima use tex cause this will be unreadable otherwise
im lost in the first line.. recurrence relations define sequences, so a_n would presumably be a sequence, not a recurrence relation
Jake The Human
$$P:f(n) \mapsto f(n)-c_1f(n-1)+c_2f(n-2)$$
Jake The Human
if we consider P to map from the space of all functions of n to all functions of n (though I'm not so sure of this)
that homomorphism idea is right!\
Consider the vector space S of functions from $\mathbb{N}\rightarrow \mathbb{R}$. This is precisely the space of all real valued sequences.\
we can define the following family ${\phi_{i}}{i=1}^{\infty}$ of linear operators from $S$ to $S$:\
define $\phi{i}(f(n)) = f(n+i)$, i,e $\phi_{i}$ returns the sequence shifted by $i$ where $i$ is a positive integer.\
now let us note that a recurrence like $f(n) + c_1f(n+1) + c_2f(n+2) = p(n)$, like the one you have written can be rewritten as $(id + c_1\phi_{1} + c_2\phi_2)(f(n)) = p(n)$ so yes, the homogeneous solution $h$ in the kernel of homomorphism $id + c_1\phi_{1} + c_2\phi_2$.
@tacit sierra is this what you were trying to say?
indeed we see that the homogeneous solutions are the kernel of the associated homomorphism
Yes, we agree on our choice of homomorphism, though I am a bit lost on why the need to define the linear operators $\phi_i$
so the homomorphism as you have presented it is a linear combination of linear operators
so that we can obtain the solutions to the homogeneous recurrence as the kernel of a linear combination of the phi_is
Why do we want the kernel to be expressed as a LC of phi_is? Maybe to see that it is a vector space wherein vectors are functions acted on by linear operators?
the kernel wont be expressed as a linear combination of the phi_is
the kernel is a set, the phi_is are functions
im saying that the kernel of the homomorphism $id + c_1\phi_{i} + c_2\phi_2$ is exactly the set of solutions to the homogeneous recurrence $f(n) + c_1f(n+1) + c_2f(n+2) = 0$
fastrack_and_backtrack
this homomorphism acting on a function f(n) I suppose. Then the kernel must be some set of functions, and I know (but I can't prove as of yet) that this kernel is a vector space
that just follows from linear algebra
the kernel of a linear map is always a subspace
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find the length of the diagonal first
that equals side length into root 2
from there u can find the side length and square that to get the area
Whats the equation
ok take a general square of side length a
Alr
can u find the length of the diagonal in terms of a
You've seen how to get the distance between two points right, with the square root
using pythagorus theorem??
Ye
Whats the equation cause i dont know the english terms
what equation
Pythagoris theorem
a^2 + b^2 = c^2??
Ok, commence par calculer la distance entre A et C (la longeur de la diagonale AC), tu trouves combien ?
Do yk thats for triangles right?
yes bro when u join the diagonal u get 2 triangles only no?
Yeah i asked this
I said idk what the equation is
ok imma just let the french guy help u
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I made this problem

