For all positive integers n > 1, xxn−1−nan−1+an(n−1) is divisible by

LetP(n):xxn−1−nan−1+an(n−1), where n>1P(2):x(x−2a)+a2=(x−a)2P(3):xx2−3a2+2a3=x3−3a2x+2a3 P(3)=(x−a)x2+xa−2a2which are divisible by (x - a)