Answer
$\emptyset$
Work Step by Step
Step 1. Provided $x\ne\pm3$, multiply $x^2-9=(x-3)(x+3)$ on both sides, we have $12=2(x+3)-3(x-3)$
Step 2. Expand the equation to get $12=2x+6-3x+9\longrightarrow 12=-x+15$
Step 3. The above gives $x=3$, however, $x\ne 3$ is the starting condition, thus, there is no solution, or the solution set is $\emptyset$
