$\frac{d^4}{dx^4}\left(\cos x\right)$

$\frac{sinx-1}{\cos\left(x\right)}-\frac{\cos\left(x\right)}{\sin\left(x\right)-1}=\tan\left(x\right)$

$\int\left(\frac{x^2-x+4}{\left(x+1\right)\left(x-4\right)}\right)dx$

$12-\left(6-3\right)-\left(2+7\right)$

$6abc+4abd+2ab$

$\lim_{x\to0}\:\frac{ln\left(cos4x\right)}{2x^2}$

$\left(8xa-10x^3\right)\:\:\left(8xa+10x^3\right)$