#### Answer

$\left\{-\frac{3}{2}, 7\right\}$

#### Work Step by Step

Add $2x^2$ and subtract $11x$ to both sides of the equation to obtain:
$$-2x^2+11x+2x^2-11x=-21+2x^2-11x
\\0=2x^2-11x-21$$
Factor the trinomial to obtain:
$$(2x+3)(x-7)=0$$
Use the Zero-Factor property by equating each factor to zero, then solve the equation to obtain:
$$2x+3=0 \text{ or } x-7=0
\\2x=-3 \text{ or } x=7
\\x=-\frac{3}{2} \text{ or } x=7$$