$\tan\left(x\right)+\:\frac{\cos\left(x\right)}{1+\sin\left(x\right)}$

$\frac{7}{x}+\frac{3x}{y}$

$\frac{6^9}{6^4}$

$\left(4a+5b^2\right)\left(4a-5b^2\right)$

$\left(-9x^2\right)\left(\frac{3}{2}x^2\right)$

$\frac{dy}{dx}\left(x+y-y^2=15\right)$

$y^3x^2dy-\left(x^2+1\right)dx=0$