$\frac{1-\sin\:\left(x\right)^6}{\cos\left(x\right)^6}$

$12x^2y^2\:-15xy^2\:-\:6x^2$

$\frac{sec\left(x\right)}{sec\left(x\right)-tan\left(x\right)}=sec\left(x\right)\left(sec\left(x\right)+tan\left(x\right)\right)$

$15a^2-6ab-8a+20-5ab-31+a^2-ab$

$\frac{3a^2\cdot4b^3c}{24ab^4}$

$\frac{+2a^2-2a}{a^2}$

$-12x^2+5x+2=0$