$\frac{\sin\theta-\cos\theta}{\sin\theta}=1-\cot\theta$

$\lim_{x\to a}\left(\frac{x^3-a^3}{a^3\cdot x-a^3}\right)$

$y+4x+y-11y-4x+11y-2x$

$-3x^2-12x-9>0$

$\int\left(-3\cos\left(\sqrt{x}\right)\right)dx$

$\lim_{x\to0}\left(\frac{e^{x^2}}{\ln\left(\frac{1}{x}\right)}\right)$

$\frac{8a^2+1}{2a+1}$