Difference between revisions of "User:Saul/algebra"

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m (Combinations/Choose)
(Combinations and Permutations)
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=== Permutations/Pick ===
 
=== Permutations/Pick ===
 
A permutation is a sequence where the order does matter.<br>
 
A permutation is a sequence where the order does matter.<br>
This is often notated by '''n pick r''' where '''n''' is the data set - say 40 lotto balls and '''r''' is the selection count - say 8 balls.
+
This is often notated by '''n pick r''' where '''n''' is the data set - say 40 lotto balls and '''r''' is the selection count - say 8 balls.<br>
 +
The general formulae for permutations is:<br>
 +
'''P = n! / (n-k)!'''
 
=== Combinations/Choose ===
 
=== Combinations/Choose ===
 
A combination is a sequence where the order does NOT matter.<br>
 
A combination is a sequence where the order does NOT matter.<br>
This is often notated by '''n choose r''' - '''n''' and '''r''' mean the same thing as in pick.
+
This is often notated by '''n choose r''' - '''n''' and '''r''' mean the same thing as in pick.<br>
 +
The general formulae for combinations is:<br>
 +
'''C = n! / ((n-k)!k!)'''<br>
 +
Also note that:<br>
 +
'''n choose k''' is the same as '''n choose (n - k)'''

Revision as of 03:24, 25 September 2019

Combinations and Permutations

Permutations/Pick

A permutation is a sequence where the order does matter.
This is often notated by n pick r where n is the data set - say 40 lotto balls and r is the selection count - say 8 balls.
The general formulae for permutations is:
P = n! / (n-k)!

Combinations/Choose

A combination is a sequence where the order does NOT matter.
This is often notated by n choose r - n and r mean the same thing as in pick.
The general formulae for combinations is:
C = n! / ((n-k)!k!)
Also note that:
n choose k is the same as n choose (n - k)