Integral of x*e^x dx

1. Use integration by parts:

   $$\int \operatorname{u} \operatorname{dv} = \operatorname{u}\operatorname{v} - \int \operatorname{v} \operatorname{du}$$

   Let $u{\left(x \right)} = x$ and let $\operatorname{dv}{\left(x \right)} = e^{x}$.

   Then $\operatorname{du}{\left(x \right)} = 1$.

   To find $v{\left(x \right)}$:

   1. The integral of the exponential function is itself.

      $$\int e^{x}\, dx = e^{x}$$

   Now evaluate the sub-integral.

2. The integral of the exponential function is itself.

   $$\int e^{x}\, dx = e^{x}$$

3. Now simplify:

   $$\left(x - 1\right) e^{x}$$

4. Add the constant of integration:

   $$\left(x - 1\right) e^{x}+ \mathrm{constant}$$

The answer is:

$$\left(x - 1\right) e^{x}+ \mathrm{constant}$$