Jika f(x) = xkuadrat2+x-1, g(x) = x-2. (f°g)(x) = 5, maka nilai x yang memenuhi....

(f o g)(x) = f (g(x)) = f(x-2) = (x-2)^2 + (x-2) - 1 = x^2 -4x +4 + x - 2 - 1 = x^2 -3x +1

(fog)(x) = 5
x^2 - 3 x + 1 = 5
x^2 -3x +1 -5 = 0
x^2 -3x - 4= 0
(x + 1)(x - 4)
x = -1 atau x = 4