jika g(x) = x² - 1 dan terdapat suatu x²- 16 fungsi f yang memenuhi (f bundaran g)^-1 (x)

g(x) = x² -1
f(x)= x² -16

(fog)⁻¹ (x) = ...
.
fog(x)= f {g(x)} = f (x² -1) = (x² -1)²  -16
fog(x) = (x² -1)² -16
(x² -1)² = y + 16
x² -1 = √(y +16)
x² = 1 - √(y +16)
x = √[1 - √(y+16)]
(fog)⁻¹(x) = √[1 - √(x+16)]