Derivative of Square Root Polynomial?

How do you find the derivative of

$\sqrt{x^2 - 4x + 4}$

I applied Chain rule and got this

$\frac{x-2}{\sqrt{(x-2)^2}}$

However, the fill-in box requires two distinct functions (piecewise) where x > ______ and x < _____.

How would I get two equations from the derivative?

Answer

Hint: $\sqrt{x^2-4x+4}=\sqrt{(x-2)^2}=|x-2|$