$mx^3+4nx^8$

$\lim_{x\to1}\left(\frac{x^2+x+2}{x^2-1}\right)$

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

$\lim_{x\to0}\left(\frac{tan6x}{sin2x}\right)$

$\frac{sin\theta\:}{cos\theta\:}$

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

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