Recent content by mathmathmad

a = - sqrt (1 - x^2) b = sqrt (1 - x^2) or should it be -1 to 1

yikes I'm sorry! didn't notice I double posted I was curious when I couldn't find my topic and thought that I haven't posted it... https://www.physicsforums.com/showthread.php?p=2955953#post2955953

a=0 b=sqrt (1 - x^2) ?

Homework Statement consider a disc of radius 1 in the plane D in R^2 D = {(x,y) in R^2 | x^2 + y^2 <=1 } what is the marginal pdf of x and y Homework Equations The Attempt at a Solution so the joint distribution of xy is 1/Pi for x^2 + y^2 <=1 right? but how exactly? "density"...

Homework Statement Consider a disc of radius 1 in the plane D in R D = {(x,y) in R | x^2+y^2 <= 1} write the marginal pdf of x and y Homework Equations The Attempt at a Solution so the joint pdf is 1/Pi for x^2 + y^2 <= 1 <- correct? but how to I get the marginal pdfs?

erm, I wrote it as augmented matrix 1 0 | 1 0 0 0 2 | 0 1 0 1 5 | 0 0 1 and start to reduce it to "reduced row echelon form" (that's why I started another thread before this asking about RRE form because I'm unsure how this works) and on the 3rd row, i get 0 0 | 0 1/2 1/5...

I'm not quite sure with my way of finding the answer, which is NO i.e. do not span would it be okay if you show me your working based on this example? :)

Homework Statement How to determine if a set of vectors span a space in general? say, V=R^n and you're given a few vectors and asked to determine if they span the space.. how do you do that? Homework Equations The Attempt at a Solution

Homework Statement [PLAIN]http://img260.imageshack.us/img260/727/picture2mg.png just wondering.. isn't the the matrix on the 1st line already in its reduced row echelon form? why is another row operation required to obtain the matrix on the 2nd line? (notice the changes to the matrix on the...

sin(x)=x - x^3/6 + x^5/120 + R erm, I take |R| = |sin x - x + x^3/6 - x^5/120 | since R_n = f(x) - T_n (which the value of n I'm not sure of but I take n=5) and there's a formula which states there exists c in (x,0) such that : R_n = f^(n+1)(c)*x^(n+1)/(n+1)! since I take n as 5...

Homework Statement find a value of h such that for |x|<h implies sin(x)=x - x^3/6 + x^5/120 + R where |R|<10^(-4) Homework Equations The Attempt at a Solution it's tedious to type out my working but I've got h= (6!/10^4)^1/6 but I'm not sure about this...

what to integrate? intergrate n^2.x^n?

Homework Statement evaluate ∑ n^2.x^n where 0<x<1 Homework Equations The Attempt at a Solution let a_n = n^2 and c=0 then radius of convergence, R=1 hence the series convergences when |x|<1 let f(x) = ∑ n^2.x^n then f'(x) = ∑ n^3.x^n-1 for n=0 to infinity then f'(x) = ∑...

is it F(x)=1/2 - x^2/2 instead? @blackscorpion : yes... I am. you too?

yeah.. so the addtion formula of f(x+y) = f(x)g(y) + f(y)g(x) right? =)