Class 11 Maths Sequences Series | Finite & infinite |

The various numbers occurring in a sequence are called its terms. We denote the terms of a sequence by a_{1}, a_{2}, a_{3}, …, a_{n}, …, etc., the subscripts denote the position of the term. The nth term is the number at the nth position of the sequence and is denoted by a_{n}. The nth term is also called the general term of the sequence.

A sequence containing finite number of terms is called a finite sequence.

A sequence is called infinite, if it is not a finite sequence.

Let a_{1}, a_{2}, a__ _{3}__,…,an, be a given sequence. Then, the expression a1 + a2 + a3 +,…+ a

Series are often represented in compact form, called sigma notation, using the Greek letter Σ (sigma) as means of indicating the summation involved. Thus, the series a_{1} + a_{2} + a_{3}+ ... + a_{n} is abbreviated as

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