please explain

Problem 3: Consider the joint probability distribution of X and Y given by ; x = 0,1,2,3 ; y = 0,1,2 0 ; otherwise (a) Compute the El XY X2 + 1 ). Your final answer must be a number. Keep 1 or more decimal places. (c) Use your results from Part b to compute E(X2). Your final answer must be a number