Chapter 9, Problem 20RE

To determine

Whether integration by parts or substitution should be used to compute the

indefinite integral ${\displaystyle \int \left(x-3\right)e^{-x}dx}$. If substitution, indicate the substitution to be made. If by parts,

indicate the functions $f\left(x\right)$ and $g\left(x\right)$ to be used.