Formulas and properties of arithmetic sequence
DefinitionArithmetic sequence (arithmetic progression) — a sequence of numbers a1, a2, a3, ..., in which each member, starting with the second, equal to the sum of the previous member and a constant number d, called the common difference.
n -th term of the sequence is given byan = a1 + (n - 1)d
an = an - 1 + d
Common differenced = an - an - 1
The sum of a finite arithmetic progression is called an arithmetic series.
Formulas of arithmetic series
|Sn =||(a1 + an) · n|
|Sn =||2a1 + (n - 1) d||· n|
Properties of arithmetic sequence
|an =||an + 1 + an - 1|
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