You are Here: Home >< Maths

# Integration watch

1. Attachment 514943514945
Question 22b is the one I'm having trouble with. On my working, the bit I've drawn a line around is my original attempt, the right bit is my second. Basically, I don't understand why it was necessary to use partial fractions to integrate that?
Attached Images

2. You can't just add the term in to both sides and integrate like that.
3. Oh god, I just realised, never mind o.o

Posted from TSR Mobile
4. (Original post by pineneedles)

Attachment 514943514945
Question 22b is the one I'm having trouble with. On my working, the bit I've drawn a line around is my original attempt, the right bit is my second. Basically, I don't understand why it was necessary to use partial fractions to integrate that?
Because what you've done there is rearrange it so that dx/dt + 2x^-2 = 2, and then somehow moved the dt over to the right hand side. If you wanted to do that, you'd have to multiply everything by dt, so that'd leave you with dx + 2x^-2 dt = 2dt and you've just gone in a circle, which is why you need to use partial fractions to get into a situation where you can actually integrate things.
5. (Original post by SeanFM)
Because what you've done there is rearrange it so that dx/dt + 2x^-2 = 2, and then somehow moved the dt over to the right hand side. If you wanted to do that, you'd have to multiply everything by dt, so that'd leave you with dx + 2x^-2 dt = 2dt and you've just gone in a circle, which is why you need to use partial fractions to get into a situation where you can actually integrate things.
(Original post by B_9710)
You can't just add the term in to both sides and integrate like that.
Indeed, hahah, I realised shortly after posting. Thanks for the explanation anyhow

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 23, 2016
Today on TSR

### Are you living on a tight budget at uni?

From budgets to cutbacks...

### University open days

1. University of Cambridge
Wed, 26 Sep '18
2. Norwich University of the Arts
Fri, 28 Sep '18
3. Edge Hill University
Faculty of Health and Social Care Undergraduate
Sat, 29 Sep '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams