Question

Inverse of f(x)= x^2 -1, x is greater than or equal to 0

Answer 1

$f(x)=x^2-1,\ x\geq0\\\\y=x^2-1\\\\\text{replace x with y and y with x}\\\\x=y^2-1\\\\\text{solve for y}\\\\y^2-1=x\ \ \ \ |+1\\\\y^2=x+1\to y=\sqrt{x+1}\\\\Answer:\ \boxed{f^{-1}(x)=\sqrt{x+1}}$