Dik fungsi f(x)=2x+1 dan (fog) (x+1) = -2x2-4x-1 nilai g(-2) =

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

x + 1 = -2 => x = -3

g(-3 + 1) = -(-3)^2 - 2(-3) - 1
g(-2) = -9 + 6 - 1 = -4

misalkan x+1=t => x=t - 1
  ( fog)(x+1) = -2x^2-4x-1
  (fog)(t) = -2(t-1)^2-4(t-1)-1
   (fog)(t) = -2(t^2-2t+1)-4t+1-1
               = -2t^2 +4t -2 -4t
                 = -2t^2-2
(fog)(x) = -2x^2-2
(fog)(x) = f(g(x))
-2x^2-2 = 2g(x)+1
2g(x)= -2x^2 -3
g(x)= -x^2 - 3/2
g(-2) = -(-2)^2 - 3/2
         = -4 -3/2
         =-11/2
maaf kalo salah.