$\int\left(e^{-20}\right)\cos\left(x\right)dx$

$\frac{x}{x^2y^2y^{-8}}$

$\lim_{x\to1}\left(\frac{1}{x-1}\right)+\left(\frac{1}{2-3x+x^2}\right)$

$3\tan\left(x\right)=2-2\tan\left(x\right)^2$

$\cos\left(\frac{\pi}{2}-x\right)=\frac{2}{7}$

$\left(3\tan^22x-10\right)\left(\tan2x+3\right)=0$

$5x^3+2x^2-4x+6-2x^3-3x^2-6x+9$