$\left(6a^2b-7c^5d^2\right)^2$

$y\:=\:\ln\left(x\right)+\ln\left(x\:-\:2\right)-\ln\left(x^2-4\right)$

$\frac{\cos x}{1-\sin x}-\sec x=\tan x$

$+9-8-7+3-\left\{-4-\left[+4\right]-8\right\}-\left(+4-3\right)$

$\frac{qr.rq8}{q^{-1}1^r}$

$7a-7b+5a+2b$

$\ln\left(e+x^2\right)=\ln\left(x\right)+\ln\left(4\right)$