# joint prob. density func.

#### teacher2be

##### New Member
Let f(x,y) = 24xy for 0<=x<=1, 0<=y<=1, 0<= (x + y)<=1
= 0 otherwise.

a. Verify that f(x,y) is a joint probability density function.
b. Find E[X].

Any suggestions for this one?

#### jerryb

##### New Member
for a. show that the double integral of f(x,y) = 1

cheers
jerry

#### BioStatMatt

##### TS Contributor
a) Be sure to consider the support when evaluating the double integral, I suggest scetching a plot of the area over x and y that will be integrated.