Difference between revisions of "User:Saul/algebra"
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=== Approximation Using Binomial === | === Approximation Using Binomial === | ||
Calculating a number to the power of another can be approximated by the following formulae:<br> | Calculating a number to the power of another can be approximated by the following formulae:<br> | ||
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'''(1 + x)<sup>n</sup> = 1 + nx + (n(n-1)x<sup>2</sup>)/2! + (n(n-1)(n-2)x<sup>3</sup>)/3! + (n(n-1)(n-2)(n-3)x<sup>4</sup>)/4! ...'''<br> | '''(1 + x)<sup>n</sup> = 1 + nx + (n(n-1)x<sup>2</sup>)/2! + (n(n-1)(n-2)x<sup>3</sup>)/3! + (n(n-1)(n-2)(n-3)x<sup>4</sup>)/4! ...'''<br> | ||
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Note: This is unending so the more steps you take the more accurate the number will be, however usually 3-4 steps is enough. | Note: This is unending so the more steps you take the more accurate the number will be, however usually 3-4 steps is enough. |
Revision as of 03:39, 25 September 2019
Contents
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)
Binomial Theorem
(a + b)n = k=0Σn ( ( n choose k ) ak bn-k )
Approximation Using Binomial
Calculating a number to the power of another can be approximated by the following formulae:
(1 + x)n = 1 + nx + (n(n-1)x2)/2! + (n(n-1)(n-2)x3)/3! + (n(n-1)(n-2)(n-3)x4)/4! ...
Note: This is unending so the more steps you take the more accurate the number will be, however usually 3-4 steps is enough.