(f + g)(x) = f(x) + g(x) Since f(x) = x3 - x , we can replace f(x) with x3 - x .
(f + g)(x) = (x3 - x) + g(x) Since g(x) = x3 + 2x2 - 10 , we can replace g(x) with x3 + 2x2 - 10 .
(f + g)(x) = (x3 - x) + (x3 + 2x2 - 10) We can drop the parenthesees.
(f + g)(x) = x3 - x + x3 + 2x2 - 10 Addition can be done in any order.
(f + g)(x) = x3 + x3 + 2x2 - x - 10 Combine like terms.
(f + g)(x) = 2x3 + 2x2 - x - 10