Diketahui g(x)=x+5 dan (g0f)(x) =x²+7x maka f(x) adalah

f(x) = x + 5
(gof)(x) = x² + 7x

maka
(gof)(x) = x² + 7x
g(f(x)) = x² + 7x
g(x + 5) = x² + 7x
g(x) = (x - 5)² + 7(x - 5)
g(x) = x² - 10x + 25 + 7x - 35
g(x) = x² - 3x - 10