find a5 and an for the geometric sequence: a1=8 and r= -5

Answer 1

The n-th term of a geometric sequence with initial value a1 and common ratio r is given by:

an = a1 ∙ r ^ ( n - 1 )

a5 = a1 ∙ r ^ ( 5 - 1 )

a5 = a1 ∙ r ^ 4

a5 = 8 ∙ ( - 5 ) ^ 4

a5 = 8 ∙ 625

a5 = 5000