$2u-11>=5u+6$

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

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

$x\left(x^2-x-6\right)$

$\lim_{x\to0}\left(e^{2x}-2x\right)^{\frac{1}{x}}$

$\frac{x^{2}+20x-9}{\left(x-3\right)\left(x-1\right)\left(x+2\right)}$

$\frac{2x+5}{6}=\frac{x}{18}$