Commonly used formulas include permutation formulas, combination formulas, repeated permutation formulas, repeated combination formulas, etc. Detailed introduction: 1. Arrangement formula: The number of ways to select m elements from n elements for arrangement: P(n, m) = n! / (n - m)!, The number of full arrangement methods for n elements: P (n, n) = n!; 2. Combination formula: Number of ways to select m elements from n elements for combination: C(n, m) = n! / (m! * (n - m)!) etc.
In permutation and combination, commonly used formulas include:
Permutation formula:
Combination formula:
Repeated arrangement formula:
Repeated combination formula:
These formulas are very useful when calculating permutation and combination problems and can help determine The total number of options and arrangements of elements. It should be noted that the premise of these formulas is that elements cannot be selected repeatedly. If elements are allowed to be selected repeatedly, repeated arrangement and repeated combination formulas need to be used.
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