Question

HELP

Determine if the sequence below is arithmetic or geometric and determine the
common difference / ratio in simplest form.
4, 20, 100

Answer 1

Explanation:

a₂ - a₁ = 20 - 4 = 16

a₃ - a₂ = 100 - 16 = 84

Since a₂ - a₁ ≠ a₃ - a₂, the sequence is not arithmetic.

a₂/a₁ = 20/4 = 5

a₃/a₂ = 100/20 = 5

Since a₂/a₁ = a₃/a₂ = 5, the sequence is geometric with a common ratio of 5.