Answer
$4\sqrt5$
Work Step by Step
$\sqrt8\times \sqrt{10}\longrightarrow$ multiplication property of square roots
=$\sqrt{80}\longrightarrow$ factor perfect square out of 80
=$\sqrt{16\times5}\longrightarrow$ multiplication property of square roots
=$\sqrt{16}\times\sqrt5\longrightarrow$ simplify
=$4\sqrt5$
