$\frac{m^4n^3}{9mn}$

$7^5.7^{-5}.7^3.8^3.8^{-6}$

$\left(-5+a\right)\left(-5-a\right)$

$\frac{x+3}{x^2+x-6}$

$\lim_{x\to\infty}\left(\frac{\log_{10}\left(\log\left(x\right)\right)}{\log_{10}\left(\log_{10}\left(x\right)\right)}\right)$

$\int\frac{x-5}{\left(x^2+1\right)\left(2x+1\right)}dx$

$\left(6-x^2\right)\left(2-x\right)$