$\lim_{x\to\frac{x}{2}}\left(\frac{18}{3-e\sec\left(x\right)}\right)$

$-13-\left(-26\right)$

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

$\left(+5\right)+\left(-4\right)\cdot\left(+6\right)$

$5\:\left(6g\:-\:7\right)\:+\:2\:\left(6\:-\:3g\right)$

$\left(\cos x-1\right)\left(\cos x+1\right)=\sin^2x$

$\left(x-15\right)\left(x+10\right)\left(x-5\right)$