$$A=2(x-2)(-x^{2}-x+3)-(-2x-1)(x-2)^{2}$$
$A=-\left(x-2\right)\left(5x-4\right)$
$x=\frac{\sqrt{9-5A}+7}{5}$
$x=\frac{-\sqrt{9-5A}+7}{5}$
$x=\frac{\sqrt{9-5A}+7}{5}$
$x=\frac{-\sqrt{9-5A}+7}{5}\text{, }A\leq \frac{9}{5}$