$20+s^2-8s$

$2y\:+\:7\left(8\:-\:4y\right)$

$\left(11h+13i\right)\left(11h-13i\right)$

$z=\cos\left(3x+4y\right),x=2t+\frac{\pi}{2},y=-t-\frac{\pi}{4}$

$\int\:\frac{sen\left(x\right)}{sen^2\left(x\right)+2cos^2\left(x\right)}dx$

$\frac{d}{dx}\left(\frac{8x+13}{15x^2+7}\right)^6$

$\int2\:\left(x^2\:+x\right).\left(2x\:+1\right)dx$