Question

A geometric sequence is shown on the graph below. What is the formula for the nth term of the sequence?

Answer 1

aₙ = 40*(1/2)ⁿ⁻¹

Explanation:

As per graph we have:

• a₁ = 40, a₂ = 20, a₃ = 10, a₄ = 5, a₅ = 2.5

So the first term is 40 and common ratio is

• 20/40= 10/20 = 5/10 = 2.5/5 = 1/2

Formula for nth term is:

• aₙ = a₁rⁿ⁻¹

• aₙ = 40*(1/2)ⁿ⁻¹