For the following arithmetical sequence, determine a1 and d and find an explicit formula for the sequence:

Question

    -8, -5, -2, 1…

a)   What is a₁?

b)   What is the common difference d?

c)    Write an explicit formula for a_n using the formula for arithmetical sequences a_n = a₁ + (n – 1)d.

Answer 1

a₁ = -8

d = - 5 - (-8) = 3

a_n = -8 + (n - 1)3