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

$\int\frac{\left(2x+7\right)}{x^2+7x+2}dx$

$12.4\cdot10^5$

$\lim_{n\to+\infty}\left(\frac{cos^2\left(n\right)}{2^n}\right)$

$\left(1+x^2\right)\frac{dy}{dx}+xy=0\:;\:y\left(0\right)=2$

$y=x\ln\left(\sqrt{1+9x^2}\right)$

$cos2x=-\frac{1}{2}$