A sequence is defined recursively by the formula an=5a n-1 with a1=4. Which of the following best describes the sequence?

Question

the n-1 is small next to the 5a

Answer 1

a₁ = 4  a_n = 5a_n-1, if n ≥ 2

 

a₂ = 5a_2-1 = 5a₁ = 5(4) = 20

 

a₃ = 5a_3-1 = 5a₂ = 5(20) = 40

 

a₄ = 5a_4-1 = 5a₃= 5(40) = 200 etc