If a, b and n are natural numbers, then a2n - 1 + b2n - 1 is divisible by
a + b
a - b
a3 + b3
a2 + b2
B.
If f is defined in [1, 3] by f(x) = x3 + bx2 + ax,such that f(1) - f(3) = 0 and f'(c) = 0, where c = 2 + , then (a, b) is equal to
( - 6, 11)
(11, - 6)
(6, 11)