$\left(7x-5y\right)\left(7x+5y\right)$

$\lim_{x\to0}\left(\frac{\sqrt{7x+1}-6}{x-5}\right)$

$\int t\left(cos\left(t^2\right)\right)dt$

$\lim_{x\to2}\left(\frac{\pi\cdot x}{3-6x}\right)$

$12x-6=7x+9$

$\int\sqrt{u}\left(u+\frac{1}{u}\right)du$

$\frac{\sqrt{x}+3-2}{x-1}$