Answer
$19i\sqrt 2$
Work Step by Step
Make the negative square roots positive by creating an imaginary number outside each radical. Then simplify the radical and combine like terms.
$5\sqrt {-8}+3\sqrt {-18}$
$5i\sqrt {8}+3i\sqrt {18}$
$10i\sqrt 2+9i\sqrt 2$
$19i\sqrt 2$
