\int {x^4 e^x dx = \left| {\begin{array}{*{20}c}
   {u = x^4 } & {dv = e^x dx}  \\
   {du = 3x^3 dx} & {v = e^x }  \\
\end{array}} \right|}  = x^4 e^x  - 3\int {x^3 e^x dx}  = ...