Which of the following is equal to the average (arithmetic mean) of (x+5)^2 and (x-5)^2?
Options:
(A) x^2
(B) x^2+2
(C) x^2 +30
(D) x^2+20
(E) x^2+25 Hmmm, my stream of consciousness:
Avg = [(x+5)^2 + (x-5)^2] / 2
Expanding and simplifying, (x^2 + 10x + 25 + x^2 - 10x + 25) / 2 = x^2 + 25 So, the answer is (E).