Integration by parts

2011-02-27 4:58 am
Int [(ln x)/x]^2 dx
the answer should be -(ln x)^2/x-2(ln x)/x-2/x+C
show me step please

回答 (4)

2011-02-27 5:18 am
✔ 最佳答案
INT [(ln x)/x]^2 dx
=INT -(ln x)^2 *(-1/x^2)dx
=INT -(ln x)^2 d(1/x)
= -(ln x)^2 * (1/x) - INT (1/x) d[ -(ln x)^2]
= -(ln x)^2 * (1/x) - INT (1/x) *[ (-2ln x) *(1/x) ]dx
= -(ln x)^2 * (1/x) +2 INT (ln x)(1/x^2) dx
= -(ln x)^2 * (1/x) -2 INT (ln x) [(-1/x^2) dx]
= -(ln x)^2 * (1/x) -2 INT (ln x) d(1/x)
= -(ln x)^2 * (1/x) -2 [(ln x)/x - INT (1/x) d(ln x)]
= -(ln x)^2 * (1/x) -2 (ln x)/x + 2 INT (1/x) (1/x) dx
= -(ln x)^2 * (1/x) -2 (ln x)/x + 2 INT (1/x^2) dx
= -(ln x)^2 * (1/x) -2 (ln x)/x + 2 (-1/x) + C
= -(ln x)^2 * (1/x) -2 (ln x)/x -2/x + C #
2011-02-27 6:09 am
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2011-02-27 5:55 am
The image cannot be seen due to some technical problem of the website.
So please click into the image link to see the solution.
2011-02-27 5:20 am
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