Answer
$5\sqrt {2}$
Work Step by Step
First, we write both numbers under the same radical:
$\sqrt {5} • \sqrt {10} = \sqrt {5 • 10}$
Multiply what is under the radical sign:
$\sqrt {50}$
Rewrite $50$ as a product of a perfect square and another factor. We can use $25$ as the perfect square factor:
$\sqrt {25 • 2}$
Take the square root of $25$ to simplify:
$5\sqrt {2}$
