Answer
$-\sqrt {10}$
Work Step by Step
$\sqrt {-2}\times\sqrt {-5}$
=$\sqrt {-1\times2}\times\sqrt {-1\times5}$
=$(\sqrt {-1}\times\sqrt {2})\times(\sqrt {-1}\times\sqrt {5})$
=$(i\times\sqrt {2})\times(i\times\sqrt {5})$
=$(i\sqrt {2})\times(i\sqrt {5})$
=$i\times i \times\sqrt 2\times\sqrt 5$
=$i^{2}\times\sqrt {2\times5}$
=$i^{2}\times\sqrt {10}$
=$(-1)\times\sqrt {10}$
=$-\sqrt {10}$
