Question

Find the common ratio of the geometric sequence 9, -18, 36,...

Answer 1

-2

Explanation:

Each term is multiplied by -2 to get the next term

Answer 2

Explanation:

All even members of the sequence are -

All odd members of the sequence are +

Ignore that for the moment and let's just find the ratio.

t_n/t_n-1 = - 2

t_2/t_n-1 = -18/9 = - 2

t_3/t_2 = 36/-18 = - 3