$\frac{4x^2+21x+48}{x+7}$

$16x^2-1=0$

$y^2-81x^2$

$\left(4m^2-5m^6\right)\left(4m^5+5m^6\right)$

$\sqrt{20^2+25^2}$

$\left(tan\left(x\right)-sin\left(x\right)sin\left(y\right)\right)dx\:+\:\left(cos\left(x\right)cos\left(y\right)\right)dy=0$

$\frac{sec\left(x\right)}{cos\:\left(x\right)}-\frac{tan\left(x\right)}{cot\left(x\right)}\:\left(x\right)=1$