Prove the validity of Eqs. (2.6-6) and (2.6-7). [Hint: Start with Eq. (2.6-4) and use the fact that the expected value of a sum is the sum of the expected values.] g(x, y) = f(x, y) + n(x, y) E{g(x, y)} = f(x, y) F(x,y) = 170(x3) Kn(x,y) (2.6-4) (2.6-6) (2.6-7)