Question

Given the definitions of f(x) and g(x) below, find the value of g(f(5)).
f(x) = 2x – 10
g(x) = x^2 + 6x – 8

I don’t need work I am just looking for the answer !

Answer 1

gf(x) = g(x^-1) = x^2 + 6x - 8

f(x) = 2x - 10

gf(x) = 6 ( 2x - 10) - 8

gf(x) = 12x- 60 - 8

gf(x) = 12x -68

gf(5) = gf(x) = 12x - 68

gf(5) = 12(5) - 68

gf(5) = 60 - 68

gf(5) = -8