Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
    • Thread Starter
    Offline

    8
    ReputationRep:
    Hey,

    Can anyone show me the working for integral of x*(1+x)^1/2 using integration by parts and also using substitution u= 1+x? I can't seem to get the right answer :/
    Offline

    20
    ReputationRep:
    (Original post by couruthim)
    Hey,

    Can anyone show me the working for integral of x*(1+x)^1/2 using integration by parts and also using substitution u= 1+x? I can't seem to get the right answer :/
    What have you tried?
    • Thread Starter
    Offline

    8
    ReputationRep:
    I tried by parts, here's my working:
    u= x, v=2/3(x+1)^3/2
    du/dx= 1, dv/dx= (x+1)^1/2

    2/3x(x+1)^3/2 - integral of 2/3(x+1)^3/2
    =2/3x(x+1)^3/2- 4/15(x+1)^5/2 + c
    Offline

    11
    ReputationRep:
    (Original post by couruthim)
    I tried by parts, here's my working:
    u= x, v=2/3(x+1)^3/2
    du/dx= 1, dv/dx= (x+1)^1/2

    2/3x(x+1)^3/2 - integral of 2/3(x+1)^3/2
    =2/3x(x+1)^3/2- 4/15(x+1)^5/2 + c
    I agree with your answer, and so does Wolfram.
    You can simplify it a little to get the result that Wolfram gives.
    • Thread Starter
    Offline

    8
    ReputationRep:
    (Original post by joostan)
    I agree with your answer, and so does Wolfram.
    You can simplify it a little to get the result that Wolfram gives.
    Ok, the simplification is the bit I don't get then, how can it be simplified to give the answer on Wolfram?
    Offline

    11
    ReputationRep:
    (Original post by couruthim)
    Ok, the simplification is the bit I don't get then, how can it be simplified to give the answer on Wolfram?
    Pull out a factor of: \dfrac{2}{15}(x+1)^{\frac{3}{2}}.
    Then simplify what remains in the usual way. It's a linear term so it's reasonably easy to rearrange into the desired form.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: November 1, 2015
Poll
Do you like carrot cake?
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

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.