## Precalculus (6th Edition)

$\left\{-\frac{3}{2}, 7\right\}$
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: $$2x+3=0 \text{ or } x-7=0 \\2x=-3 \text{ or } x=7 \\x=-\frac{3}{2} \text{ or } x=7$$