Integral help

[Oliver Curtis]

Hi stuck on the following:

Integral xcos^3(1/x). As in 'cos one over t (then the whole thing to the power three). Ive watched loads of first year calculas videos and re gone over both calculas lectures weve had and I just keep going round in circles trying to do it by parts. Ive tried multiple substitutions and nothings getting me there. Its just nothing like ive seen before. Ive got first load of assessments next week and this has got me stumped and a little worried!

Thanks guys.

 

[Deleted member 4993]

Hi stuck on the following:

Integral xcos^3(1/x). As in 'cos one over t (then the whole thing to the power three). Ive watched loads of first year calculas videos and re gone over both calculas lectures weve had and I just keep going round in circles trying to do it by parts. Ive tried multiple substitutions and nothings getting me there. Its just nothing like ive seen before. Ive got first load of assessments next week and this has got me stumped and a little worried!

Thanks guys.

Did you try substitution:

u = 1/x

 

[Steven G]

I agree with Subhotosh Khan. I (almost) always let the angle be u if it more complicated then x, y, t, ....
Then if needed I make another substitution.
Please try what was suggested and post back with what you get.