Jika ( f dot g )= 4x kuadrat+8x-3 dan g(x)= 2x+4 maka nilai dari f invers x adalah

(fog) (x) = 4x²+8x-3
f(2x+4)=4x²+8x-3
misal
t= 2x+4
2x=t-4
x= t-4 / 2

f(x) = 4(t-4/ 2)²+8(t-8/2)-3
=(t²-8t+16) + 4t-32-3
=t²-4t-19

jadi
f(x) = x²-4x-19

cari inversnya
y = x²-4x-19
y + 23 = x²-4x-19+23
y + 23 = x²-4x+4
y+23= (x-2)²
(y+23)^½ = x-2
x=-2+√(y+23)
f-¹(x) = -2+√(x+23)