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# Binomial watch

1. Please can you help, I think i'm going wrong but i'm not sure how.
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2. (Original post by Louise_1988)
Please can you help, I think i'm going wrong but i'm not sure how.

P.S. please ignore the fact I couldn't get the divide by factorials underneath, I know they should be there. Sorry.
Aha, have you forgot to use the factorials for the coefficients??
3. (Original post by zazy)
Aha, have you forgot to use the factorials for the coefficients??
I have changed it, is this now right??
4. (Original post by Louise_1988)
I have changed it, is this now right??
Yeah, that should do the trick!!!
5. (Original post by zazy)
Yeah, that should do the trick!!!
Thanks
6. An easier way is just to change it to

(1/5)^6(x/5 - 1)^6

And just use the nCr notation instead of using the factorials etc..
7. The coefficients are still wrong!
they should be,

1 6 15 20 15 6 1

I use Pascal's triangle to get these numbers. It's usually a lot faster.

In the third term, where you have,

5(4)x^4(-5)²
-------------
2!

that should have been,

6(5)x^4(-5)²
-------------
2!

and so on for the other terms. They should have started with the number 6, rather than 5.
8. (Original post by Fermat)
The coefficients are still wrong!
they should be,

1 6 15 20 15 6 1

I use Pascal's triangle to get these numbers. It's usually a lot faster.

In the third term, where you have,

5(4)x^4(-5)²
-------------
2!

that should have been,

6(5)x^4(-5)²
-------------
2!

and so on for the other terms. They should have started with the number 6, rather than 5.
aah... I realise I have made a rather fundamental mistake, will have to re-do it. Thanks for pointing it out.

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