Question

Masih hangat nih,cemilannya,yuk santap

jika f(x)=x+3 dan (gof)(x)=2x^2+4x-3 tentukan nilai (fog)(1)

Answer 1

(gof)(x) = g(f(x)) = 2x²+4x-3
              g(x+3) = 2x²+4x-3
misal. x+3 = m --> x = m-3
g(m) = 2(m-3)²+4(m-3)-3
       = 2(m²-6m+9)+4(m-3)-3
       = 2m²-12m+18+4m-12-3
g(m) = 2m²-8m+3
g(x) = 2x²-8x+3

(fog)(x) = f(g(x))
(fog)(1) = f(g(1))
           = f(2.1²-8.1+3)
           = f(-3)
           = -3+3
           = 0