$\sqrt{9}\sqrt{2}$

$2\sqrt{9}\sqrt{3}$

$\sqrt{16}\sqrt{2}\sqrt{b^2}\sqrt{b}$

Your answer will need absolute value. A variable can usually represent any number. In this case, when a square root is taken, the answer is always positive. For example:

$\sqrt{(-5)^2}=5\text{ (not }-5)$