Mathematics

Mathematics

Problem

Evaluate ∫x3ex dx\displaystyle \int x^{3}e^{x}\,dx.
Intuitive explanation

This is an integration by parts problem where you'll need to apply the technique repeatedly. The key insight is to choose u=x3u = x^3 (so its derivatives get simpler) and dv=ex dxdv = e^x\,dx (since exe^x stays manageable). Each application of integration by parts reduces the power of xx by one, so you'll repeat the process three times until the polynomial term vanishes and you're left with just exe^x to integrate.

Intuitive explanation

This is an integration by parts problem where you'll need to apply the technique repeatedly. The key insight is to choose u=x3u = x^3 (so its derivatives get simpler) and dv=ex dxdv = e^x\,dx (since exe^x stays manageable). Each application of integration by parts reduces the power of xx by one, so you'll repeat the process three times until the polynomial term vanishes and you're left with just exe^x to integrate.

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