Consider the function $f(x)=\sqrt[\phantom{2}]{4-x}.$

Find the formula for the inverse function.

$f^{-1}(x)=4+x^2$

$f^{-1}(x)=\frac{1}{\sqrt[\phantom{2}]{4+x}}$

$f^{-1}(x)=4-x^2$

$f^{-1}(x)=\frac{1}{\sqrt[\phantom{2}]{4-x}}$