$2x+33y=90$

$\lim_{x\to1}\left(\frac{1-x^2}{2-\sqrt[2]{x^2+3}}\right)$

$28u^2-63$

$\lim_{x\to\pi}\left(\frac{cos\left(7x\right)}{x-\pi}\right)$

$\frac{4}{n+1}-\frac{1}{n^2+7n+6}=\frac{3}{n^2+7n+6}$

$\lim_{x\to0}\left(\frac{x^3-4x^2+5x}{x}\right)$

$0.\left(-17\right)=-17$