TITLE: Question about integration by parts?
QUESTION [5 upvotes]: For this problem I did the integration by parts and got that answer. But for some reason it is still wrong. Does anyone get any different answers? Any hints or suggestions would be of great help! Thanks!

REPLY [2 votes]: You would have to make $u= ln(x)$ and $du= (1/x)$. Then you would make $dv= x^3$ and v would then = $x^4/4$. Using the integration by parts formula, which is the integration of u dv = uv- integration of $vdu$. Substitute in your variables and your answer should be $(ln(x) x^4/4) - (x^4/16) + C$.