13. Since f(x, y) = f(y, x) for all (x, y), it follows that the marginal p.d.f.'s will be the same. Each of those marginals will equal the integral of f(x, y) over the other variable. For example, to...

Extracted text: 13. Since f(x, y) = f(y, x) for all (x, y), it follows that the marginal p.d.f.'s will be the same. Each of those marginals will equal the integral of f(x, y) over the other variable. For example, to find f1(x), note that for each , the values of y such that f(x, y) > 0 form the interval [-V1 – x², 1 – x2]. Then, for -1<>