Given f(x) = x^2 + 2x and g(x) = 6 − x2 find (f + g)(x)

A.) (f + g)(x) = 2x + 6

B.) (f + g)(2x) + 2x + 6

C.) (f + g)(x) = 2x^2 + 8x

D.) (f + g)(x) = 2x^2 + 6