Answer
The solution is $y=-\frac{3}{4}$
Work Step by Step
$2y=\sqrt 5y+6$
Square both sides:
$(2y)^2=(\sqrt 5y+6)^2$
$4y^2=5y+6$
$4y^2-5n-6=0$
$(y-2)(4y+3)=0$
$y-2=0$ or $4y+3=0$
$y=2$ or $y=-\frac{3}{4}$
With $y=2$
then $2(2)=\sqrt 5(2)+6$
$4=4$
With $y=-\frac{3}{4}$
then $2(-\frac{3}{4})=\sqrt 5(-\frac{3}{4})+6$
$-\frac{3}{2} \ne \frac{3}{3}$
Hence, the solution is $y=-\frac{3}{4}$