$2.5\cdot2-5$

$\tan^2x=\sec^2x-\cos^2x\sec^2x$

$\frac{x^2-9}{x+1}$

$\frac{26}{0.37}$

$\frac{\cos\left(x\right)}{1+\csc\left(x\right)}.\frac{1-\csc\left(x\right)}{1-\csc\left(x\right)}$

$\left(\:4x\:-\:8\:x^3\:\right)\:\left(\:6x\:+\:7\right)\:$

$\left(3y-x\right)\cdot\left(5x^2+7xy-2y^2\right)$