$\left(3n+2b\right)\left(3n-2b\right)$

$25g^2-9g^2$

$7a^2b+14a^3b-21a^5b$

$\lim_{x\to\infty}\left(\frac{3x^2-2x+1}{x^3+4}\right)$

$\frac{4.01\:\:-4}{\left(4.01\right)^2-3\left(4.01\right)-4}$

$\left(x-15\right)\left(x-25\right)$

$\frac{d}{dx}\left(\frac{2}{\sqrt[4]{5}}-\frac{1}{\sqrt{x}}+\frac{3}{x^{-1}}\right)$