$2\left(2x-5\right)\left(2x+5\right)-\left(x-1\right)^2$

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

$\left(x+10\right)\left(x+12\right)$

$\lim_{x\to\infty}\left(\frac{2^x}{x}\right)$

$\left(\frac{5}{\left(x-3\right)}\right)+\left(\frac{3}{\left(x+7\right)}\right)+\frac{1}{2}$

$\frac{6}{x-1}\ge5$

$\lim_{x\to\infty}\left(6\sqrt{x^2+7x}-6x\right)$