Let \( I\) =\(∫\)\(x^2 log\ x\ dx\)
Taking \(log\ x\) as first function and \(x^2\) as second function and integrating by parts, we obtain
\(I= log\ x∫[x^2dx-∫{(\frac {d}{dx}log\ x)∫x^2dx]}dx\)
\(I= log\ x(\frac {x^3}{3})-∫\frac 1x.\frac {x^3}{3}dx\)
\(I=\frac { x^3log\ x}{3}-∫\frac {x^2}{3}dx\)
\(I= \frac {x^3log\ x}{3}-\frac {x^3}{9}+C\)
The number of formulas used to decompose the given improper rational functions is given below. By using the given expressions, we can quickly write the integrand as a sum of proper rational functions.
For examples,