Diketahui g(x) = x+4(fog) (x) = x² + 2x – 8tentukan f (x)​

Jawaban:

g(x) = x + 4

fog(x) = x^2 + 2x – 8

f(x)…?

fog(x) = f(g(x))

x^2 + 2x – 8 = f(x + 4)

misal x + 4 = a

x = a – 4

f(a) = (a – 4)^2 + 2(a – 4) – 8

f(a) = a^2 – 8a + 16 + 2a – 8 – 8

f(a) = a^2 – 6a

ganti a menjadi x sehingga

f(x) = x^2 – 6x