#math - Mon 9 Apr 2007 between 00:14 and 01:47

NY Lost Funds



kmh_afkl
bsmntbombdoodkinky
% Factor[a*x^4 + b*x^3 + c*x^2 + d*x + e]
mbotbsmntbombdood: e + d*x + c*x^2 + b*x^3 + a*x^4
bsmntbombdoodlame
KRUSHGROOVEHi.
TemplarianSimple Stats problem i'm stuck on multiple choice: The diameter of ball bearings is known to be normally distrbuted with unknown mean and variance. A random sample of size 25 gave a mean 2.5cm. The 95% confidence interval had length 4cm. Then... (A): The sample variance is 4.86. (B). The sample variance is 26.03. (C).The population variance is 4.84. (D). The population variance is 23.47. (E). The sample variance is 23.47. (T
winuxhello all
to find the nullspace of a matrix, do I just set the matrix equal to zero and find its reduced row echelon form?
FatalErrormore or less, you just solve Ax = 0
holstwinux: if you have access to Matlab you can QR factorize for a ortogonal basis of both ran(A) and null(A)
its pretty much the gram schmidth procedure in action for both parts
winuxi have to do it by hand on my test tomorrow
holsthmm
SafroleYou sound like an overachiever.
you better slow down.
holst:P
winuxi actually did it before, but it sort of flew out of my memory
holstso how do you do it by hand. hmm
FatalErroryou had the right idea with what you said before
http://en.wikipedia.org/wiki/Nullspace has an example
winuxmm ty
holstthat will get the job done. however i dont like their procedure
what is that "z=z" nonsense
FatalErrorit means it's a free variable
holstessentially they have two equations on R^3 space; thats the intersection of two non-affine planes; the nullspace is the intersection between them; a line. i would like some geometric side notes on the explanation
on the / as a
FatalErrorthe fact that there is 1free variable should be enough to see that it's a line really
godtviskenTo find the power series of sin x/x I can just divide each term of the power series of six x by x, right?
six/sin*
so sin x is x - x^3/6 + x^5/120 ..
and sin x/x would be 1 - x^2/6 + x^4/120 ?
Kasadkad`Yeah
godtviskenKasadkad`: is there a theorem that says this?
Kasadkad`Sure, the "Just Erase Those Three Dots And It's A Polynomial Theorem"
It's like how you prove things in multivariable calculus by taking the single variable version and making all the letters bold
But yes
It just follows from the fact that multiplying power series works exactly like multiplying polynomials
So you can factor out an x
billfurA great example until you come to partial derivatives of pratial derivatives.

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NY Lost Funds