Question

Diketahui f(x) = 2x + 3 dan g(x) = 3x - 1 . Nilai x yang memenuhi (fog)(x-4) = f(x) + 2 g(x) adalah

Answer 1

F(g(x-4)) = 3(x-4) - 1
               = 3x - 13
f(3x-13) = 2(3x-13) + 3
             = 6x - 26 + 3
             = 6x - 23

(fog)(x-4) = f(x) + 2 g(x)
6x - 23 = 2x + 3 + 2(3x - 1)
6x - 23 = 8x + 1
8x - 6x = - 23 - 1
2x = - 24
  x = -12