$6x^2-2xy+5x-x^2+4xy-8x$

$\frac{dy}{dx}=\frac{x-xy}{xy-y}$

$-3a^2b+7ab+7a^3b^2-8a^2b-5ab$

$\lim_{x\to0}\left(\frac{\left(x^2+3x\right)}{e^x-1}\right)$

$\left(2c^3+2c^2-50c-50\right)\left(x+1\right)$

$\frac{\csc\left(a\right)-\sec\left(a\right)}{\sec\left(a\right)}$

$3\cdot3^{\sqrt{x-6}}$