Geometric Sequence Formula

A geometric sequence is a sequence in which each term is obtained by multiplying the previous term by a constant ratio. That constant is called the common ratio.

nth Term Formula

aₙ = a₁rⁿ⁻¹

Here, a₁ is the first term, r is the common ratio, and n is the position of the term.

Sum of a Finite Geometric Sequence

Sₙ = a₁(1 − rⁿ) ÷ (1 − r), when r is not equal to 1.

Example

For 3, 6, 12, 24, the first term is 3 and the common ratio is 2. The fifth term is 3 × 2⁴ = 48.