The Student Room Group

Maths C4 Integration - tricky question needing help

Hi there,

I'm having trouble with the following question:

Unparseable latex formula:

\[\textup{Show that }\int_{1}^{e}\frac{1}{x^2}\textup{ln}\textup{ }\textup{dx}=1-\frac{2}{e}\]\]



(^ I don't know why there's a "p" in there, please ignore it...)


I think I've got the answer of the intergration (by parts):

Unparseable latex formula:

\left [\frac{1}{3}x^{-3} \right ]_{1}^{e}\]



Which means when I put the limits in I get:

13e313\frac{1}{3e^{3}}-\frac{1}{3}


I have no idea how to turn this into what they want. I might have got the integration wrong but have been over that many times.

Any help much appreciated, cheers!
Reply 1
You've integrated incorrectly.

Integrate by parts again
Reply 2
Aggghhh, turns out I thought the integral of lnx was 1/x and not the other way round, so used the wrong parts.

Many thanks, Cephalus!
Reply 3
Original post by jhex6
Aggghhh, turns out I thought the integral of lnx was 1/x and not the other way round, so used the wrong parts.

Many thanks, Cephalus!


Lol its no problem. It happens sometimes:tongue:

Quick Reply

Latest

Trending

Trending