Question

1. g(x) = 2x-1 dan (fog)(x) = 4x-9 maka f(7)
2. f(x) =√x-4 dan (fog)(x) = 4x maka g(x)

Answer 1

1. (fog)(x) = f(g(x)) = 4x-9 <=> f(2x-1) = 4x-9 <=> f(2x-1) = 2(2x-1)-7 <=> f(y) = 2y-7.

Sehingga f(7) = 2(7)-7 = 7.

2. Diketahui: f(x) = 
(fog)(x) = 4x <=> f(g(x)) = 4x <=>  = 4x <=> g(x)-4 = 16x² <=> g(x) = 16x²-4 = 4(4x²-1)

Answer 2

1) f(2x - 1) = 4x - 9
untuk x = 4 maka:
f(7) = 4(4) - 9 = 7

2) √(g(x) - 4) = 4x
g(x) - 4 = 16x²
g(x) = 16x² + 4