f(x)=2x+4 dan (g o f)(x)=4x^2 +12x+6 maka tentukan g(x)

Ikutan ah..

f(x) = 2x + 4

g(f(x)) = 4x² + 12x + 6
g(2x + 4) = (2x + 4)² - 2(2x + 4) - 2
g(x) = x² - 2x - 2 ✔

jawab

f(x ) = 2 x+ 4
gof(x) = 4x² + 12x + 6
g{2x+4} = 4x² + 12x + 6
2x + 4 = a
2x = a -4
x = 1/2 a - 2

g(a) = 4 (1/2a - 2 )² + 12(1/2 a -2) + 6
g(a) = 4(1/4 a²- 2a + 4) + 6a - 24 + 6
g(a) = a² - 8a + 16 + 6a - 18
g(a) = a² - 2a - 2
g(x) = x² - 2x - 2