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nickymarden
Group Title
does anyone want to teach me Multivariable Calculus? :P
 2 years ago
 2 years ago
nickymarden Group Title
does anyone want to teach me Multivariable Calculus? :P
 2 years ago
 2 years ago

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amistre64 Group TitleBest ResponseYou've already chosen the best response.1
you know what you did to x in calc 1 and 2? now do it to y and z
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
im good with matrices and all that. it's when it comes a part of vectors that i'm not understanding really well
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
dw:1334382554391:dw
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
vector just point in a direction
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
wait, ill show u
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
good, casue i aint none to goog at mindreading :)
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
... or typing lol
 2 years ago

ald0024 Group TitleBest ResponseYou've already chosen the best response.0
I'm in the same position! Some teacher failed me along the way in the vector department!
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
given vectors a=2xi+2xj+xk, b=xi2xj+2xk and c=2xixj2xk show that {a,b,c} is a negative orthogonal base for x<0
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
an orthogonal base is such that each vector is orthogonal to each other
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
since x is a common factor of everyting; we can ignore it
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
for wich value(s) of x, will {a,b,c} be an orthornomal base?
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
a.b =2xi+2xj+xk, xi2xj+2xk  2  4 + 2 = 0 b.c=2xixj 2xk xi2xj+2xk  2 + 2  4 = 0 a.c =2xi+2xj+xk, xi2xj+2xk  2  4 + 2 = 0 so it is orthonormal
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
i did that, but when it comes to the second part i get lost.
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
and since x is just a common "scalar" id assume x can be anything; but maybe zero since people hate zeros
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
i got this:
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
" Moreover, they are all required to have length one" http://mathworld.wolfram.com/OrthonormalBasis.html
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
\[a=\sqrt{4x^2+4x^2+x^2}=\sqrt{9x^2}=3x\]
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
looks like x needs to be the 1/... yeah, that
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
so i did it for all 3 vectors and they all were 3x
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
x is the scalar that makes them go unit i believe; which means the x = 1 over magnitude
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
so since a=b=c=3x=1 > x=1/3
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
x is not part of the length; its factored out and eqauted to the reciprocal of the magnitude
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
each vector has the same basic components so they are going to have the same lengths <2,2,1> ; sqrt(4+4+1) = sqrt(9) = 3 x = 1/3 yep
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
there's a third part :X
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
and the negative is just 1/3 right?
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
Find the coordinates to v in the orthornomal base obtained, in wich v in the canonical base has coordinates (1,2,3)
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
now your just making up words :P
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
im sorry, its in portuguese, i'm translating :P
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
or trying anyway
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
standard basis perhaps?
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
row reduce your vector basis next to this new vector from the standard bases
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
how should we define our vectors in the basis? what should our x y and z parts correlate to?
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
or does it matter?
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
i did it like this
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
it matters; switching columns of a matrix alters things; switching rows doent
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
for the first vector and i did the same to the other 2
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
v1=2,2,1 v2=1,2,2 v3=2,1,2 \[\frac{1}{3}\begin{vmatrix}v_1&v_2&v_3\\2&1&2\\2&2&1\\1&2&2\end{vmatrix}\ \begin{vmatrix}c_1\\c_2\\c_3\end{vmatrix}=\begin{vmatrix}1\\2\\3\end{vmatrix}\]
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
your vectors need to be put in columns, not rows
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
multiply both sides by 3 to get rid of the scalar
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
ooh yeah
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
\[RREF\begin{vmatrix}2&1&2&&3\\2&2&1&&6\\1&2&2&&9\end{vmatrix}\]
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
the left goes to identity and the right goes to the coord vector in the basis
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
got it.
 2 years ago

nickymarden Group TitleBest ResponseYou've already chosen the best response.2
guess im not as bad as i thought? at least i got the first 2 parts correct :p and thanks for explaining the rest :))
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.1
youre welcome :)
 2 years ago

Rogue Group TitleBest ResponseYou've already chosen the best response.0
I'd like to learn multivariate as well to get a head start on next year, but I'm not a fan of matrices and vectors :(
 2 years ago
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