$\lim_{x\to-\infty}\left(\frac{\sqrt{x^6-x}}{x^3+1}\right)$

$\lim_{x\to\infty}\left(\frac{e}{2x+\ln\left(5x\right)}\right)$

$\left(2x^7y^5\right)^3$

$\lim_{n\to\infty}\left(\frac{\left(2n+1\right)^2}{2n^2+3n+1}\right)$

$x-6=62$

$\frac{3^2}{4}-ab+b^2$

$x^2-4y^2+20=0$