$\lim_{x\to\pi}\sin\left(x\right)\cot\left(x\right)\left(1+\tan^2\left(x\right)\right)$

$\frac{4b^3}{a^2}-\frac{9a^3}{b^2}$

$0.28-1.04-4.2+8.6+0.65$

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

$\frac{1}{4}x^2y^4-\frac{4}{36}m^2n^6$

$66+45-165-123+867$

$x ^ { 2 } - 8 x + 11 = 0$