Question

which function below is the inverse of f(x) = x^2-9

Answer 1

to find the inverse
replace f(x) with y
switch all x and y
solve for y
replace y with f⁻¹(x)

f(x)=x^2-9
y=x^2-9
x=y^2-9
x+9=y^2
sqrt both sides
$\sqrt{x+9}$
replace
f⁻¹(x)=$\sqrt{x+9}$

that is the inverse