$\lim\:_{x\to10}\left(\frac{1}{x+10}-\frac{1}{\sqrt{x+10}}\right)$

$ay-by$

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

$\left(9-4\right)-\left(6-2\right)+\left(12-4\right)-\left(7-9\right)$

$6x-3y$

$\lim\:_{x\to\:\infty}\left(\frac{6x+11}{3x^2-7x+9}\right)$

$2dy=4dx$