Answer
$\{ 16\}$
Work Step by Step
Step 1. Rewrite the equation as $\sqrt x=x-12$
Step 2. Take square on both sides to get $x=x^2-24x+144$ or $x^2-25x+144=0$
Step 3. Factor and solve the equation: $(x-9)(x-16)=0$, thus $x=9, 16$
Step 4. Check answers in the original equation, only $\{ 16\}$ fits.
