Question

Find the 8th term of the geometric sequence 5, -15, 45

Answer 1

a₈ = - 10935

Explanation:

the nth term of a geometric sequence is

`a_(n)` = a₁
`(r)^(n-1)`

where a₁ is the first term and r the common ratio

here a₁ = 5 and r =
`(a_(2) )/(a_(1) )` =
`(-15)/(5)` = - 3 , then

a₈ = 5 ×
`(-3)^(7)` = 5 × - 2187 = - 10935