9. Let X and Y be independent and identically distributed random variables with mean / and variance oz. Find the following: (a) E[(X + 2) 2] (b) Var(3X + 4) (c) E[(X - Y) 2] (d) Cov{ (X + Y), (X - Y) } 10. The moment generating function of the random variable X is given by Mx(t) = exp{2et - 2} and that of Y by My(t) = (et + !)" Assuming that X and Y are independent, find (a) P{ X + Y = 2}. (b) P{ XY = 0}. (c) E(XY )