Find the integral $\int\frac{3x\sin\left(x\right)}{\cos\left(x\right)^4}dx$

Find the integral

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

Find the integral

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

Find the integral

$\int dx$

Find the integral

$\int1dx$

Find the integral

$\int\left(3t^2+\frac{t}{2}\right)dx$

Find the integral

$\int\left(\pi^2-1\right)dx$

Find the integral

$\int\left(\frac{t^2}{2}+4t^3\right)dt$