Answer
$\{-2\}$
Work Step by Step
Step 1. Rewrite the equation as $\sqrt {3x+7}=1-\sqrt {x+2}$
Step 2. Take square on both sides to get: $3x+7=1-2\sqrt {x+2}+x+2$ or $x+2=-\sqrt {x+2}$
Step 3. Take square on both sides again to get: $x^2+4x+4=x+2$ or $x^2+3x+2=0$ which gives $x=-1,-2$
Step 4. Check answer in the original equation: only $\{-2\}$ fits.