Hi guys,(adsbygoogle = window.adsbygoogle || []).push({});

I'm really stuck on the following questions, not sure as to how to approach it:

Let X and Y be random variables for which the joint pdf is as follows:

f(x,y) = 2(x+y) for 0 <= x <= y <= 1

and 0 otherwise.

Find the pdf of Z = X + Y

And also:

Suppose that X is a random variable for which the mgf is as follows:

/u(t) = e^(t^2 + 3t) for minus infinity < t < infinity

Find the mean and variance for X.

I know that the answers are 3 and 2 respectively, but was unsure how they got to the answer, do I need to integrate by parts?

Any help would be appreciated! Thanks guys :)

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# Joint pdf question and mgf

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