$\frac{27^{n-1}}{9^n}$

$30\cdot6$

$\frac{\frac{1}{\tan\left(x\right)}}{\sec\left(x\right)}+\frac{-\cos\left(x\right)}{\sec\left(x\right)+\tan\left(x\right)}$

$\left(3x+2\right)\left(x+3\right)$

$625=x^2$

$cosx\left(e^2^y-y\right)\frac{dy}{dx}=e^ysen2x\:$

$8x^2-y^2=1$