You forgot to change the limits of integration after you made the substitution.
Integral of 1/[(x^5)(9x^2-1)^(.5)] dx from sqrt(2)/3 to 2/3.
everyway i try it, it seems to be wrong!! i have been doing this problem for hours! i need help
here is my work: http://i198.photobucket.com/albums/a...n/scan0002.jpg
http://i198.photobucket.com/albums/a...scan0003-1.jpg
also I am not sure if #15 on the second link is correct either.
First substitute u = 3x with dx = (1/3) du
so the integrand becomes
Then substitute:
note that:
and the integrand becomes:
which reduces to
OR
The integral of the fourth power of the cosine function is:
(12 x + 8 Sin[2 x] + Sin[4 x])
----------------------------
32
I hope this helps.