Diketahui (g°f)(x)=2x2+4x+5 dan (x)=2x+3 .tentukan rumus fungsi f(x)

Diketahui
(gof)(x) = 2x² + 4x + 5
g(x) = 2x + 3

Ditanya
f(x) = ?

Jawab
(gof)(x) = 2x² + 4x + 5
g(f(x)) = 2x² + 4x + 5
2(f(x)) + 3 = 2x² + 4x + 5
2(f(x)) = 2x² + 4x + 5 - 3
2(f(x)) = 2x² + 4x + 2
2(f(x)) = 2 (x² + 2x + 1)
f(x) = 2(x² + 2x + 1)/2
f(x) = x² + 2x + 1

gof (x) = 2x^2 + 4x + 5 dan g(x) = 2x +3
g { f (x) } = 2x^2 +4x +5
2.f (x) + 3 = 2x^2 + 4x +5
2.f(x) = 2x^2 + 4x +5 -3
2.f (x) = 2x^2 + 4x + 2
f (x) = (2x^2 + 4x +2)/2
f (x) = x^2 + 2x +1