Question

If f(x) = x2 − 2x + 9 and g(x) = 8 − x, what is (f o g)(−4)?

Answer 1

(f•g)(x)=f(g(x))
$f(g(x)) = {(8 - x)}^{2} - 2(8 - x) + 9 \\ when \: x = - 4 \\ f(g( - 4)) = {(8 + 4)}^{2} - 2(8 + 4) + 9 \\ f(g( - 4)) = {12}^{2} - 2 \times 12 + 9 \\ f(g( - 4)) = 144 - 24 + 9 = 129$