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FP3 expansion and limits watch

1. Can anyone explain to me the 4th line down for solution A? I don't understand why they start taking the terms away from 1 and then adding terms to the power of 2 and multiplying those terms by -1x-2 / 2! etc. Confusing the hell out of me.
2. (Original post by kingm)

Can anyone explain to me the 4th line down for solution A? I don't understand why they start taking the terms away from 1 and then adding terms to the power of 2 and multiplying those terms by -1x-2 / 2! etc. Confusing the hell out of me.
It's just the binomial expansion of
3. (Original post by Mr M)
It's just the binomial expansion of
Oh i see. But why have they started using it there? I would have thought that the solution would have ended at the third line?
4. (Original post by kingm)
I would have thought that the solution would have ended at the third line?
I don't understand why you would think that. The question as set would not have been answered.
5. (Original post by Mr M)
I don't understand why you would think that. The question as set would not have been answered.
Clearly i don't understand, hence i'm asking for help. Maybe you can explain it to me?
6. (Original post by kingm)
Clearly i don't understand, hence i'm asking for help. Maybe you can explain it to me?
I would if I could get my head around what your problem is!

As I explained, the question asks you to find the first few terms of a series in ascending powers of x. If you stop at line 3, you will have failed to do this.
7. (Original post by Mr M)
I would if I could get my head around what your problem is!

As I explained, the question asks you to find the first few terms of a series in ascending powers of x. If you stop at line 3, you will have failed to do this.
Ok. What i'm not understanding is how they get from the 3rd line to the 4th line. The third line you have all of the terms to the power of -1. I get that. But the 2nd line they start taking terms from 1 and raising them to the power of 2 etc. It's the first time they've done it in the book, and it's the only example they use it in. I just don't get it.
8. (Original post by kingm)
Ok. What i'm not understanding is how they get from the 3rd line to the 4th line. The third line you have all of terms to the power of -1. I get that. But the 2nd line they start taking terms from 1 and raising them to the power of 2 etc. It's the first time they've done it in the book, and it's the only example they use it in. I just don't get it.
Can you write down the expansion of as far as the term in ?
9. (Original post by Mr M)
Can you write down the expansion of as far as the term in ?
Ok i actually get it now. Appreciated. Just go easy on me as i haven't studied maths for 7years now and i'm majorly rusty.

Are you able to give me some pointers on questions 4 and 5 here....

10. (Original post by kingm)
Ok i actually get it now. Appreciated. Just go easy on me as i haven't studied maths for 7years now and i'm majorly rusty.

Are you able to give me some pointers on questions 4 and 5 here....

Good. I didn't realise I wasn't going easy on you!

Questions 4 and 5, do you know the product rule for differentiation? You will find stationary points when dy/dx = 0.
11. (Original post by Mr M)
Good. I didn't realise I wasn't going easy on you!

Questions 4 and 5, do you know the product rule for differentiation? You will find stationary points when dy/dx = 0.
Oh yeah! Thats all i needed. Ta.

I'll be back for more :-)

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