Hi , I'm totally lost on this question and answer attached . Please the full simplified working for both parts would be greatly appreciated .

Thank you

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- Nov 25th 2012, 11:30 AMminicooper58Sigma notation factorials
Hi , I'm totally lost on this question and answer attached . Please the full simplified working for both parts would be greatly appreciated .

Thank you - Nov 25th 2012, 11:50 AMcoolgeRe: Sigma notation factorials
1. (r+1)! - (r-1)! = (r+1)r(r-1)! - (r-1)! Take (r-1)! as common factor and simplify.

2. Just expand : 2! - 0! +

3! - 1! +

4! - 2! +

......

(n-1)! - (n-2)! +

n! - (n-2)! +

(n+1)! - (n-1)!

Cancel the terms ans add the rest. - Nov 25th 2012, 12:57 PMminicooper58Re: Sigma notation factorials
Hi , thank you for part a) and the terms in b) but I am still struggling with how they arrive at the proof given after cancelling the terms .

Any help would be appreciated .

Thank you - Nov 25th 2012, 01:02 PMcoolgeRe: Sigma notation factorials
The terms that are not cancelled are (n+1)! + n! - 1! -0! = n!(n+1+1) - 2. Hope this helps!

- Nov 25th 2012, 02:56 PMtopsquarkRe: Sigma notation factorials