$\tan\left(a\right)\cdot\cot\left(a\right)\cdot\sec\left(a\right)=\frac{1}{\cos\left(a\right)}$

$\ln\left(\frac{x^6\sqrt{x-1}}{3x-18}\right)$

$3\ln\left(e^5\right)$

$x\ge6-x$

$8\:-\:6:\:\left(-\:3\right)\:+\:4.\:\left(-\:2\right)\:-\:3.\:\left(-\:4\right)\:$

$2m-3n-\left|-3n+2n\right|$

$\left(\frac{3}{4}m-\frac{2}{3}n\right)^2$