You are Here: Home

# Integration by substitution

Maths and statistics discussion, revision, exam and homework help.

Announcements Posted on
1. Integration by substitution

Use a substitution to show

I used u = a - x and got the required result then

Hence evaluate I in terms of a

I have no idea of how to start I was thinking that and but I don't know how to proceed.

Please don't post the full solution I want to do it by myself as much as possible.

Cheers
2. Re: Integration by substitution
Hint: Can you write the numerator (in the second form of I) another way so that the fraction can be split up?

Spoiler:
Show
Last edited by notnek; 18-04-2012 at 16:18.
3. Re: Integration by substitution
(Original post by notnek)
Hint:
Ah ok so

So

So ?
4. Re: Integration by substitution
(Original post by TheJ0ker)
Ah ok so

So

So ?
Yes, that's right. Can you finish it off or did you stop because you were stuck?
5. Re: Integration by substitution
(Original post by notnek)
Yes, that's right. Can you finish it off or did you stop because you were stuck?
No I can finish off from there. It's amazing how something simple like that can completely change a fairly nasty looking integral, I need to be sharper next time. Thanks for the help.
6. Re: Integration by substitution
(Original post by TheJ0ker)
No I can finish off from there. It's amazing how something simple like that can completely change a fairly nasty looking integral
I'm with you on this - I used to like these kinds of questions. Is this a STEP/AEA question or has A level maths become harder?

And the more tricky integrals you do, the sharper you'll get. Next time you see a question with two forms of the same integral I, there's a good chance that you'll know what to do.
7. Re: Integration by substitution
(Original post by TheJ0ker)
Ah ok so

So

So ?

(Original post by notnek)
Yes, that's right. Can you finish it off or did you stop because you were stuck?
I tried helping, but i got stuck

however, i have a question now,

How did ytou get from So
to

I'm probably being a bit dim, have i forgotten some special rule?

DOESN'T MATTER
I thought the - I was inside the integral, didnt take into account the fact that dx came before it! duh!

so yes, i was being dim
Last edited by elldeegee; 18-04-2012 at 16:47.
8. Re: Integration by substitution
(Original post by notnek)
I'm with you on this - I used to like these kinds of questions. Is this a STEP/AEA question or has A level maths become harder?

And the more tricky integrals you do, the sharper you'll get. Next time you see a question with two forms of the same integral I, there's a good chance that you'll know what to do.
Yeah this is a STEP q. These are the kind of questions I go straight for when I start a new paper, I really like them. I am a bit slow at the moment with them but hopefully in the 9 weeks I have left I will get much better.

## Step 2: Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank

this is what you'll be called on TSR

2. this can't be left blank

never shared and never spammed

3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. By completing the slider below you agree to The Student Room's terms & conditions and site rules

2. Slide the button to the right to create your account

You don't slide that way? No problem.

Last updated: April 18, 2012
Study resources