Math 2.0

definition

Real sequence

Definition

A real sequence is a sequence in the set R\mathbb{R} of real numbers. Thus it is a function a ⁣:N→Ra \colon \mathbb{N} \to \mathbb{R}, and each term ana_n is a real number.

Remarks

Examples are an=1/(n+1)a_n = 1/(n + 1), an=(−1)na_n = (-1)^n and an=2na_n = 2^n. The real sequences form a real vector space under the termwise operations (an)+(bn)=(an+bn)(a_n) + (b_n) = (a_n + b_n) and c (an)=(c an)c\,(a_n) = (c\,a_n). The limit of a sequence is defined first for real sequences in most courses.

Explanations

L1 human

A real sequence is an endless list of real numbers a0,a1,a2,…a_0, a_1, a_2, \dots. You can draw it as points (n,an)(n, a_n) in the plane, one point for each natural number nn.

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Sources

  1. Web https://en.wikipedia.org/wiki/Sequence, Limits and convergence