#### Answer

$x=\pm \sqrt {5}$ or, $x=+\sqrt {5},-\sqrt {5}$

#### Work Step by Step

Given: $8x^2=40$
This can be written as: $x^2=\dfrac{40}{8}$
or, $x^2=5$
Apply The Square Root Property.
$x=\sqrt{5}$
Hence, $x=\pm \sqrt {5}$ or, $x=+\sqrt {5},-\sqrt {5}$