Question

Given the definitions of f, of, xf(x) and g, of, xg(x) below, find the value of g, of, f, of, minus, 5, .g(f(−5)).
f, of, x, equals, x, plus, 12
f(x)=
x+12
g, of, x, equals, x, squared, minus, 2, x, minus, 15
g(x)=
x
2
−2x−15

Answer 1

f(-5) = -5 + 12 = 7.
g(f(-5)) = g(7) = 7^2 − 2·7 − 15 = 49 − 14 − 15 = 20.