Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    Can anyone integrate: sin(theta) * e^(2k*theta) with respect to theta (k is a constant

    I got: ((e^(2k*theta))/(4k^2-1))(2ksin(theta)-cos(theta)) + c

    when i used integration by parts, however the answer book says that it should be (4k^2 +1) where I've got (4k^2-1)

    Please help, thnx in advance
    Offline

    10
    ReputationRep:
    Let I denote the integral. Then integrating by parts twice yields:
    I = -e^(2kx) cos(x) + 2k e^(2kx) sin(x) - 4k^2 I
    => (4k^2 + 1) I = e^(2kx) (2k sin(x) - cos(x)) + C
    • Thread Starter
    Offline

    0
    ReputationRep:
    I dont get the same thing as you by integrating by parts twice, bugger, I know I've made a mistake but can work out where
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: February 5, 2006

University open days

  • Southampton Solent University
    All faculties Undergraduate
    Sun, 18 Nov '18
  • University of Bradford
    All faculties Undergraduate
    Wed, 21 Nov '18
  • Buckinghamshire New University
    All Faculties Postgraduate
    Wed, 21 Nov '18
Poll
Black Friday: Yay or Nay?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Equations

Best calculators for A level Maths

Tips on which model to get

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.