Thread: Combinations
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Old November 6th, 2009, 07:45 AM
courteous courteous is offline
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Choosing x elements out of set of n elements (z_1, ..., z_n) and disregarding their order is the definition of combinations.

F(x, z_1, ..., z_n) = \frac{n(n-1)...(n-x+1)}{x!}=\frac{n!}{(n-x)!x!}={n \choose x}
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