$\lim_{x\to0}\left(1-\sin\left(3x\right)^{\frac{1}{x}}\right)$

$\cot\cdot\frac{\csc x}{\sec x}$

$\lim_{x\to0}\left(\frac{sin2x}{2x^2+x}\right)$

$\int\left(6x+2\right)\left(-e^{-x}\right)dx$

$e^{4xyz}-z=x^2$

$81\left(a+b\right)^4-\left(x+y\right)^2$

$dx=4\cos\left(\theta\:\right)d\theta$