Integration by Parts for ∫ xlnx/(x^2-1)^(1/2)dx

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SUMMARY

The discussion focuses on the integration of the function ∫ xlnx/(x^2-1)^(1/2)dx using integration by parts. The substitution x=secT and the differential dx=secTtanTdT are employed to simplify the integral. The final result is expressed as (x^2-1)^(1/2)lnx - (x^2-1)^(1/2) + sec^-1x + C. The discussion highlights the importance of recognizing exact integrals for efficient problem-solving.

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Homework Statement



I(xlnx/(x^2-1)^(1/2),x)
x=secT ; dx=secTtanTdT
I(secTln(secT)secTtanTdT/tanT,T)
I(sec^2Tln(secT),T)
u=ln(secT) du= secTtanTdT/secT = tanTdT
dv=sec^2Tdt v=tanT
tanTln(secT)- I(tan^2T,T)
tanTln(secT)-I(sec^2-1,T)
tanTln(secT)-tanT+T+C
T=sec^-1x
secT=x
tanT= (x^2-1)^(1/2)
tanTln(secT)-tanT-T= (x^2-1)^(1/2)lnx-(x^2-1)^(1/2)+sec^-1x+C

Homework Equations





The Attempt at a Solution


 
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Hi nameVoid! :smile:

(have an integral: ∫ and a square-root: √ and try using the X2 tag just above the Reply box :wink:)

Yes, that looks correct, but you could have missed out a lot in the middle if you'd noticed that x/√(x2 - 1) is an exact integral, so you can integrate by parts immediately. :wink:
 

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