Question

Which of the following are geometric sequences?

Check all that apply.

a.1, 4, 9, 16, 25, 36, 49

b. 1, 2, 4, 8, 16, 32

c. 10, 5, 2.5, 1.25, 0.625, 0.3125

d. 2, -2, 2, -2, 2, -2, 2

Answer 1

so b, c, and d work?

Answer 2

a(n+1) = k a(n)
a(n+1)/a(n) = k, so look for common ration for consecutive terms

Three of these series are geometric. Yes, you are right. b,c,d