$\int_{- \infty }^{0} xe^xdx$

$\int_{-\infty}^0\left(xe^x\right)dx$

$\int_{-\infty}^0xe^xdx$

$\int_0^{\infty}\left(\frac{1}{\sqrt{x}+x^2}\right)dx$

$\int_3^{\infty}4e^{\left(2x-4\right)}dx$

$\int_3^{\infty}\left(4e^{\left(2x-4\right)}\right)dx$

$\int_0^1\left(\frac{ln\left(x\right)}{x}\right)dx$

$\int_0^{\infty}\left(1+2x\right)e^{-x}dx$