Question

Let f(x) = x2 − 81. Find f−1(x). (1 point)

±square root of the quantity x plus 81
9 square root of x
1 over quantity x squared minus 81
x squared over 81

Answer 1

\sqrt{x+81

Explanation:

f(x)= x^{2} -81

y=x^{2} -81

x=y^{2}-81

x+81=y^{2}

\sqrt{x+81=y

Answer 2

let y = f(x) = x^2 - 81
y + 81 = x^2
x = sqrt(y + 81)
switch y to x, x to y
y = sqrt(x + 81) = f-1(x)