What is (f+g)(x)?
f(x) = x^3 -x
g(x) =x^3+2x^2-10
(f+g)(x) = ?
(f + g)(x) means f(x) + g(x) = [ x^3 - x ] + [ x^3 + 2x^2 - 10 ] = 2x^3 + 2x^2 - x - 10
