$\frac{\cos\left(a\right)}{1-\sin\left(a\right)}-\frac{\cos\left(a\right)}{1+\sin\:\left(a\right)}$

$\sqrt{112}$

$3x\frac{dy}{dx}=\frac{6}{7y}$

$\left(3x^2y-x^2\right)\cdot\left(3x^2y+x^2\right)$

$\frac{d}{dx}\ln\sqrt[3]{8x^2+7}$

$-2\cos\:\left(x\right)\cos\:\left(5x\right)$

$x^2+6x-55$