Relation Between Equidistant Terms of an AP

Relation Between Equidistant Terms of an AP

## Formula

For an AP with $$n$$ terms:

$$a_r+a_{n-r+1}=a_1+a_n$$

More generally, terms equidistant from the beginning and end have a constant sum.

## Example Form

$$a_1+a_n=a_2+a_{n-1}=a_3+a_{n-2}$$

## Usage

- Used to simplify sums and establish relationships between symmetric terms.