$\lim_{x\to\frac{\pi}{4}}\left(\cot\left(x-1\right)\cdot\sec\left(2x\right)\right)$

$\left(x\log\left(2\right)\right)+\left(x\log\left(3\right)\right)=\left(x\log\left(4\right)\right)$

$25-2\cdot4$

$\lim_{x\to-\infty}\left(\frac{\sqrt{x^6+3x^4-18}}{x^3-7x+5}\right)$

$\frac{36a^2}{42a^6}$

$\lim_{x\to1}\left(\frac{x^3-1}{4x^3-x-1}\right)$

$am-2bm-3an+6bn$