You are Here: Home >< Maths

# Partial Fractions Help watch

1. Express 1 − t^2 / t^2(1 + t 2) in partial fractions.

So i got the whole A/t + B/t^2 + (Ct + D)/( t^2 + 1)

Put t=0 and got B= 1. Now how do I get A C and D? If I put t=3, I get 3 variables and I just don't know how to get those three.

Thanks
2. (Original post by ChemBoy1)
Express 1 − t^2 / t^2(1 + t 2) in partial fractions.

So i got the whole A/t + B/t^2 + (Ct + D)/( t^2 + 1)

Put t=0 and got B= 1. Now how do I get A C and D? If I put t=3, I get 3 variables and I just don't know how to get those three.

Thanks
Can you please post the identity you're considering i.e. the line of working after A/t + B/t^2 + (Ct + D)/( t^2 + 1) ?
3. (Original post by ChemBoy1)
Express 1 − t^2 / t^2(1 + t 2) in partial fractions.

So i got the whole A/t + B/t^2 + (Ct + D)/( t^2 + 1)

Put t=0 and got B= 1. Now how do I get A C and D? If I put t=3, I get 3 variables and I just don't know how to get those three.

Thanks
Put t=-1 and t=1 then solve a system of 3 eqs in 3 variables
4. (Original post by RDKGames)
Put t=-1 and t=1 then solve a system of 3 eqs in 3 variables
Comparing coefficients gets the answer quickly without the need for solving a system of equations.
5. (Original post by Notnek)
Comparing coefficients gets the answer quickly without the need for solving a system of equations.
So it does.
Didn’t look at it for long enough.
6. Is there not an easier way, it was only a 4 mark question, solving a 3 variable equation sees to much, is there not a simpler way?
(Original post by RDKGames)
Put t=-1 and t=1 then solve a system of 3 eqs in 3 variables
7. (Original post by ChemBoy1)
Is there not an easier way, it was only a 4 mark question, solving a 3 variable equation sees to much, is there not a simpler way?
Yes, comparing coefficients as I mentioned above. Try it and post your working if you get stuck.
8. (Original post by ChemBoy1)
Is there not an easier way, it was only a 4 mark question, solving a 3 variable equation sees to much, is there not a simpler way?
Compare coefficients as said above.

The simplest/quickest way to solve it is by saying:

...then cancel the common terms in both fractions to be left with the answer.

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: February 17, 2018
Today on TSR

### University open days

• Sheffield Hallam University
Wed, 17 Oct '18
• Northumbria University
Wed, 17 Oct '18
• Staffordshire University
Wed, 17 Oct '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