$\lim_{z\to\infty}\left(\frac{z-1}{z^2-1}\right)$

$\frac{4x^5+2x^3-3x\:+1}{x^2-2}$

$7x^2y+14x^2-3y-8x^2-9xy+3x^2y$

$y=\frac{\left(x^2+3\right)^{\frac{2}{3}}\left(3x+2\right)^2}{\sqrt{x+1}}$

$4c+5c$

$\left(x^3+y^3\right)\left(x^6-x^3y^3+y^6\right)$

$\frac{x^3+8^3}{x+2}$