$-5\left(yz+3\right)-7yz+1+y^2$

$m^3-4m^2n+5m^3-7mn^2-4m^2n+5m^3$

$tan^2\left(x\right)+5tan\left(x\right)-36=0$

$53=\arctan\left(\frac{x}{50}\right)$

$\lim_{x\to-2}\left(\frac{\left(x-2\right)e^{\frac{2}{x}}}{4x}\right)$

$-18\:-\:\frac{7}{-1}$

$\lim_{x\to0}\left(\frac{xcos6x}{cos19x}\right)$