$8a\:+9a$

$\left(-\frac{1}{2}\left(-\frac{51}{571}-\frac{311}{250}\right)-\frac{2}{3}\right)+\left(\frac{\sqrt{3}}{2}\left(-\frac{51}{571}+\frac{311}{250}\right)\right)i$

$1x^2-24x+c$

$\left(2^{-2}\right)^{-2}$

$xy-y'=e^{\left(-x^2\right)}y^3$

$x^2+3x+4-2x^2-2x+5+3x^2+5x-7$

$x=4s+2t$