$55-\left(66-2\right)$

$\frac{x}{\frac{1}{2}}$

$\lim_{x\to\infty}\left(\frac{21x^3-2x^2+x-3}{x^3+2x^2-x+1}\right)$

$\lim_{x\to\infty}\left(\frac{1+\sqrt{x}}{4\log\left(x^2+1\right)}\right)$

$\lim_{x\to0}\left(\frac{\sqrt{y+16}-4}{y}\right)$

$\left|-4\right|+\left|4\right|$

$\int\frac{x-4}{x^2-x+\:2}dx$