Question

Write an explicit formula for an, the nth term of the sequence 75, 15, 3, ....

Answer 1

aₙ = 75 x 0.2ⁿ⁻¹ or 75 x (1/5)ⁿ⁻¹

Explanation:

a₁ = 75

a₂ = 75 x 0.2¹ = 75 x 0.2 ²⁻¹ = 15

a₃ = 75 x 0.2² = 75 x 0.2³⁻¹ = 3

.......

aₙ = 75 x 0.2ⁿ⁻¹ or 75 x (1/5)ⁿ⁻¹