Question

for the function f(x)=x^2-12 find (f^-1)(4)

Answer 1

f(x) = x^2 - 12
y = x^2 - 12
y + 12 = x^2
x = sqrt(y + 12)
(f^-1)(x) = sqrt(x + 12)

(f^-1)(4) = sqrt(4 + 12) = sqrt(16) = 4
(f^-1)(4) = 4