Answer
$\sqrt {5x+6} +2 =0$
$x=-2/5$ is the extraneous solution
Work Step by Step
$\sqrt {5x+6} +2 =0$
$\sqrt {5x+6} =-2$
$(\sqrt {5x+6})^2 =(-2)^2$
$5x+6=4$
$5x=-2$
$5x/5=-2/5$
$x=-.4$
$\sqrt {5x+6} +2 =0$
$\sqrt {5*(-2/5)+6} +2 =0$
$\sqrt{-2+6} +2 =0$
$\sqrt {4} +2=0$
$2 + 2 \ne0$
$4 \ne 0$