$\frac{1-\sin\theta}{\cos\theta}+\frac{\cos\theta}{1-\sin\theta}=2\sec\theta$

$\lim_{x\to\pi}\frac{\sin\left(4x\right)}{\sin\left(3x\right)}$

$\frac{d}{dx}x^3\ln x^2$

$\left[\left(x^2-2x\right)+3\right]\left[\left(\left(x^2-2x\right)-3\right)\right]$

$\int\left(e^{2x}\cdot\:cosx\right)dx$

$-4x+6y-2+5x-5y+2$

$xy'-2y=x^3e^x$