$\frac{\tan\left(x\right)+\cos\left(x\right)}{\sin\left(x\right)}=\sin\left(x\right)+\cot\left(x\right)$

$\cos\left(\frac{4\pi}{9}\right)cos\left(\frac{\pi}{9}\right)+\sin\left(\frac{4\pi}{9}\right)sin\left(\frac{\pi}{9}\right)$

$\lim_{x\to0}\left(\frac{x+3\tan\left(x\right)}{\sin\left(x\right)}\right)$

$4\int_1^{\infty}\left(\frac{1}{x\sqrt{2x^2-1}}\right)dx$

$28-\left[-21-\left(12-3\right)-7\right]$

$\frac{x\left(x^2-4\right)}{x\left(x-2\right)}$

$4x^2=3x+1$