$f=-12xy+19yx-4xy+7y$

$\frac{d}{dx}\left(\frac{1}{\left(x+3\right)^2}\right)$

$\left(2x^2-3x-5\right)\left(2x+8\right)$

$\cos a\sec a=1$

$\left\{-\left[\left(20+4\right).5-8\right].\left(11-18\right)\right\}-\left\{5+\left[3-132:-2\right].7\right\}$

$\frac{d}{dx}\sqrt{\frac{2x^2}{1-x^2}}$