$y'=xe^x,\:y\left(0\right)=1$

$\frac{\tan\left(x\right)}{1}-\frac{\tan\left(x\right)^2}{\tan\left(x\right)^2}$

$\left(5+z^2\right)\left(5-z^2\right)$

$9x^4-24x^2y^2+16y^4$

$\left(x+\frac{4}{5}\right)^2$

$\infty^{-0.0000000000001}$

$\cos y=\cos\left(60^{\circ\:\:}-y\right)$