$\frac{x^{-1}y-1}{x^{-2}-y^{-2}}$

$4y-8x+2b-4x+5y+8b$

$\left(3x^3-\frac{1}{2}x^2+2x-1\right)+\:\left(-\frac{1}{4}+2x^2-5x^3\right)$

$\left(\frac{2}{5}yw^3-\frac{1}{10}xw^5+3zw^4\right)^2$

$2^5\:x\:2\:^4\:x\:2\:$

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

$\left(4-2x\right)^2\left(1-2x\right)^2$