Factorial question

Forums Algebra Factorial question

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This topic contains 2 replies, has 3 voices, and was last updated by Avatar of philippgrinev philippgrinev 2 years, 3 months ago.

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February 23, 2012 at 5:09 pm #429
Avatar of jerry79
jerry79
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Last Monday the teacher explained to us the concept of “factorial”. I don’t get it.

February 23, 2012 at 8:09 pm #440
Avatar of 2plus2
2plus2
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Simply stated, the factorial of ANY given integer is simply the product of all its prior integers starting with 1 leading up to AND including the given integer itself.

Examples….

3!=1x2x3

6!=1x2x3x4x5x6

May 30, 2012 at 2:17 pm #678
Avatar of philippgrinev
philippgrinev
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As you have just started factorials, I believe you only need to know about the factorials of positive integers. The factorial of a positive integer is all the integers from 1 all the way to that integer inclusive multiplied together. So n! = 1*2*3*…*n.
From this definition, we can also simplify many expressions involving factorials, e.g. 1*2*3*4*…*(n-3)*(n-2)*n – this is very much like n!, but here we miss out, as I tried to show, the number n-1. But then, as we miss it in a product, we can just divide that product by what we miss! So we can write that as n!/(n-1). Hope you understand the logic now! If you have any more questions, feel free to e-mail me at filipp-grinyov@yandex.ru
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“If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is.
― John von Neumann

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