Precalculus (6th Edition) Blitzer

a. $\sqrt {x-2}$ b. $[2,\infty)$
Given $f(x)=\sqrt x, x\geq0$ and $g(x)=x-2$, we have: a. $(f\circ g)(x)=\sqrt {x-2}$ b. The domain of the above function can be found as $\{x|x\geq2\}$ or $[2,\infty)$