- #1
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Homework Statement
How is possible this equality:
[tex] {n \choose k} = \frac{n \cdot (n-1) \cdots (n-k+1)}{k(k-1)...1} = \frac{n!}{k!(n-k)!}[/tex]
? I mean where the second part [tex]\frac{n!}{k!(n-k)!}[/tex] comes from?
Note that:Ok, I understand about:
[tex]
\frac{n!}{(n-k)!} = n \cdot (n-1) \cdot \cdot \cdot n-k+1
[/tex]
But still I can't understand why n! is written like that..
Written like what?Ok, I understand about:
[tex]
\frac{n!}{(n-k)!} = n \cdot (n-1) \cdot \cdot \cdot n-k+1
[/tex]
But still I can't understand why n! is written like that..