Question

Which of the terms best describes the following sequence?

13, 26, 39, 52, ...

Group of answer choices

Arithmetic

Geometric

Neither

Answer 1

It's both an A. P and a G. P series.

Explanation:

Let's prove using A.P with a common difference (d) = 13

Let's say we want to find the second number

a + (n - 1)d

a = 13, n = 4, d = 13

.: S2= 13 + ( 2- 1)13

S2= 13 + (1) 13

S2= 13 + 13 = 26

Let's show using a G. P series.

S2 = arⁿ—¹

S2 = 13 × 2²—¹

S2 = 13 × 2¹

S2 = 13 × 2 = 26