calculus - Integration by parts or substitution?

$$\int_{}^{}x e^x \mathrm dx$$

One of my friends said substitution , but I can't seem to get it to work.
Otherwise I also tried integration by parts but I'm not getting the same answer as wolfram.

The space in the question seems like it shouldn't take more than 2 lines though. Am I missing something?

Thanks to all the answers below , I messed up in the original question it was actually

$$\int_{}^{}x e^{x^2} \mathrm dx$$

With help from the below answers I did the following:

Let $u = x^2$ , then $du=2x\mathrm dx$

So rewriting the integral

$$\int_{}^{}{{x\cdot e^u} {1 \over 2x}} \mathrm dx$$

Simplifying yields:

$${1 \over 2x}\int_{}^{}{e^u}\mathrm dx$$

Which in turn yields:

$${\frac{e^u}{2}} + C$$

The rest is fairly obvious!

Answer

Definitely by parts, as substitution of $x$ won't get you anywhere.
Let $u=e^x$ and $dv=e^x$ in $\int udv=uv-\int vdu$
and we have

$$
\int xe^xdx=xe^x-\int e^x dx=xe^x-e^x+c
$$

As a general tip, you will usually want to use parts if you have an exponential, which doesn't get any nastier as you anti-differentiate, and a polynomial which will disappear after some number of differentiations. A notable exception is when you have something like
$$
\int xe^{x^2}dx
$$
Where a $u=x^2$ substitution will cancel out the $x$ coefficient on the exponential.