Prove the trigonometric identity $\sec\left(x\right)=\frac{\sin\left(2x\right)}{\sin\left(x\right)}+\frac{-\cos\left(2x\right)}{\cos\left(x\right)}$

Find the integral

$\int x^3sin\left(x\right)dx$

Find the integral

$\int\left(3x^2+1\right)^6dx$

Find the integral

$\int12x^5dx$

Find the integral

$\int xsinx\:dx$

Find the integral

$\int\left(\frac{\cos\left(x\right)}{x}\right)dx$

Find the integral

$\int\left(x^3+2\right)^23x^2dx$

Find the integral

$\int\frac{cos\left(x\right)}{x}dx$