Question

Determine the value of c so that the following functions represent the joint pmf of
the random variables X and Y .
i) f (x, y) = c(x + y +1), x = 0, 1, 2, 3 and y = 0, 1, 2 .
ii) f (x, y) = c(x^2 + y^2), x = −1, 1 and y = −2, 2