Answer
{$\pm 5\sqrt 2)$}
Work Step by Step
Given: $3x^2-150=0$
Take the common terms out.
$3(x^2-50)=0$
This can be written as: $[x^2-(5\sqrt{2})^2]=0$
$(x-5\sqrt 2)(x+5\sqrt 2)=0$
Thus, $x=\pm 5\sqrt 2 $
Hence, $x=${$\pm 5\sqrt 2)$}