$400n^2-169m^2$

$\left(\frac{12nm}{4n^3m^{-2}}\right)^3$

$\lim_{x\to2}\left(\frac{4x^2-5x-6}{x}\right)$

$\lim_{x\to0}\left(\frac{e^2-\cos\left(x\right)}{2e^x.\sin\left(x\right)}\right)$

$3-2\log_{\frac{1}{2}}\left(2x-4\right)$

$\lim_{x\to-5}\left(\frac{\sqrt{21+3x}-4x+2}{\sqrt[3]{3}x\:-6x+8}\right)$

$57^2$