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**debjit625****Member**- Registered: 2012-07-23
- Posts: 91

I can't solve this one ...

Find n ,if

Thanks

*Last edited by debjit625 (2012-12-03 20:08:48)*

Debjit Roy

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The essence of mathematics lies in its freedom - Georg Cantor

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 90,444

Hi;

n = 49.

Solve this:

(n+2)(n+1) = 2550

**In mathematics, you don't understand things. You just get used to them.**

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,528

hi debjit625

So you just need to solve

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**debjit625****Member**- Registered: 2012-07-23
- Posts: 91

Ok I have seen this in my book too but ,I didn't understood how

expands into ,is their any special rules or am I missing something very basicDebjit Roy

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The essence of mathematics lies in its freedom - Georg Cantor

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 90,444

Hi;

(n+2)! = (n+2)(n+1)**n (n-1)(n-2)(n-3)...1**

n! =**n (n-1)(n-2)(n-3)...1**

(n+2)! = (n+2)(n+1)**n!**

**In mathematics, you don't understand things. You just get used to them.**

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**debjit625****Member**- Registered: 2012-07-23
- Posts: 91

Now I got it thanks guys, it was so simple ,my book didnt have enough of factorials its more about permutation can you guys give me some resource on factorials...

Thanks

Debjit Roy

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The essence of mathematics lies in its freedom - Georg Cantor

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 90,444

Hi;

In order of difficulty.

http://www.mathsisfun.com/numbers/factorial.html

http://www.purplemath.com/modules/factorial.htm

**In mathematics, you don't understand things. You just get used to them.**

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**debjit625****Member**- Registered: 2012-07-23
- Posts: 91

I know about mathisfun ,I meant some advance stuff

Thanks again...

___________________________________________________

The essence of mathematics lies in its freedom - Georg Cantor

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 90,444

Hi;

Please check post #7, they get more and more difficult.

**In mathematics, you don't understand things. You just get used to them.**

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**debjit625****Member**- Registered: 2012-07-23
- Posts: 91

Thanks bobbym for the link http://www.themathpage.com/aprecalc/factorial.htm

as I was searching factorial problems involving variables and it had some great stuff.

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The essence of mathematics lies in its freedom - Georg Cantor

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 90,444

Hi debjit625;

You are welcome.

**In mathematics, you don't understand things. You just get used to them.**

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