If f(x)= x^2 + 2x

Question

What is f(-x)
What is f(1/a)

Thanks!

Answer 1

f(-x) = (-x)^2 + 2(-x) = x^2 - 2x

f(1/a) = (1/a)^2 + 2(1/a) = 1/a^2 + 2/a