#### Answer

$5 \sqrt{2}$

#### Work Step by Step

In order to simplify a radical, we consider the factors of the number inside of the radical. If any of these factors are perfect squares, meaning that their square root is a whole number, then we can simplify the radical. We know that 25 and 2 are factors of 50. We know that 25 is a perfect square, so we simplify:
$ \sqrt{25} \sqrt{2}=5 \sqrt{2}$