$\lim_{x\to0}\left(\frac{x^2}{cos\left(\frac{\pi}{6}x\right)-1}\right)$

$\int\left(1-2x^9\right)dx$

$\frac{\cos\:\left(\theta\:\right)-\sec\:\left(\theta\:\right)}{\sin\:\left(\theta\:\right)}$

$-1-2-1$

$-3\left(-4\right)+\left(-2\right)$

$x\left(\frac{cos\pi}{6}-\frac{ctg\pi}{3}\right)=\frac{ctg\pi}{6}+\frac{cos\pi}{6}$

$\frac{2x^3+x}{x+3}$