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

$y'-xy=x^3$

$-7\cdot13\cdot\left(-4\right)$

$\left(\:x+2y\right)\:\left(2y-x\right)$

$\lim_{x\to\infty}\left(ln\left(2x^2+1\right)-ln\left(x^2-1\right)\right)$

$\lim_{x\to\frac{\pi}{6}}\left(\frac{\sqrt{3}sinx\:-\:cosx}{x-\frac{\pi}{6}}\right)$

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