g(x)=x-3 dan (f o g) =x^+2x-5, fungsi f(x)

g(x)= x-3
(fog)(x)=x² + 2x -5
dit: f(x)=..?
jwb: (fog)(x)= f [g(x)]= x² + 2x -5
                   = f(x-3)= x² + 2x- 5
                          x² + 2x -5 
               f(x)= ----------------
                           x-3
semoga membantu,maaf kalau salah

Diketahui:
g(x) = x-3
(f o g)(x) = x^2 + 2x - 5

Ditanyakan:
f(x) = ...?

Jawab:
(f o g)(x) = f(g(x))
x^2 + 2x - 5 = f (x - 3)
Misalkan x - 3 = a, x= a + 3
(a + 3)^2 + 2(a + 3) - 5 = f(a)
a^2 + 6a + 9 + 2a + 6 - 5 = f(a)
a^2 + 8a + 10 = f(a)
x^2 + 8x + 10 = f(x)

Bukti:
(f o g)(x) = f(g(x))
= (x - 3)^2 + 8(x - 3) + 10
= x^2 - 6x + 9 + 8x - 24 + 10
= x^2 + 2x - 5

Semoga membantu