How do I properly integrate (x^3)(e^(x^2))?

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SUMMARY

The integral ∫x³e^(x²)dx cannot be solved using elementary functions, as confirmed in the discussion. The correct approach involves using substitution effectively, particularly the substitution method applied earlier in the problem. The final solution is expressed as (e^(x²)x²/2) - (1/2)e^(x²) + C. Participants emphasized the importance of recognizing when to avoid integrating e^(x²) directly due to its complexity.

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Homework Statement



Use both substitution and integration by parts to solve:

∫x3ex2dx

2. The attempt at a solution

∫x3ex2dx

∫ex2x3dx

(1/2x)ex2x3-∫(1/2x)ex23x2dx

(1/2)ex2x2-(3/2)∫ex2xdx

(ex2x2/2)-(3/2)∫eux(du/2x)

(ex2x2/2)-(3/2)(1/2)∫eudu

(ex2x2/2)-(3/4)eu + C

(ex2x2/2)-(3/4)ex2 + C

The solution is supposed to be; (ex2x2/2)-(1/2)ex2 + C

Where am i going wrong?
 
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You assumed that ∫ex2dx = ex2/(2x). That's not true.

You do not want to take the route of trying to integrate ex2. No matter how hard you try you will not be able to find that integral. This integral cannot be expressed in terms of elementary functions. You need to take another approach.

Hint: That u-substitution you used to solve ∫xex2dx might come in handy if you use it earlier on.
 
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Solved it. Thanks a lot!
 

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