$\left(-a'\frac{\sin\left(x\right)\:}{\cos\left(x\right)}\right)\left(-\sin\left(x\right)\right)+\left(a'\:\cos\left(x\right)\right)=cscx$

$\lim_{x\to\infty}\left(-.5ln\left(x^2+1\right)\right)$

$\frac{\left(cos^2x+1\right)}{cos^2x}$

$-2\cdot23$

$\left(x+1\right)^3-x^3$

$\frac{1}{8}c^9-\frac{1}{125}d^{12}$

$xy'-y=x^2sen\:x$