Chapter 10 - Radical Expressions and Equations - 10-4 Solving Radical Equations - Practice and Problem-Solving Exercises - Page 637: 47

The solution is $y=\frac{3}{2}$.

$\sqrt y+12=3\sqrt y$ Square both sides: $(\sqrt y+12)^2=(3\sqrt y)^2$ $y+12=9y$ $8y=12$ $y=\frac{3}{2}$ With $y=\frac{3}{2}$ then $\sqrt \frac{3}{2}+12=3\sqrt \frac{3}{2}$ $3\sqrt \frac{3}{2}=3\sqrt \frac{3}{2}$ Hence, the solution is $y=\frac{3}{2}$.