$\frac{4}{0.32}$

$\cos\left(x\right)+\cos\left(x\right)\cdot\frac{\sin\left(x\right)^2}{\cos\left(x\right)^2}$

$3\cos2\left(x\right)$

$\left(1-7a\right)\left(1-6a\right)$

$\frac{\left(2x^2\right)^3}{4x^4}$

$\frac{dy}{dx}=\frac{x^2+3y^2}{xy}$

$x\frac{dy}{dx}+\left(1+x\right)y-e^{-x}\sin\left(2x\right)$