determine whether each sequence is geometric, find the common ration
1) -2, 4, -8, 16
2) 1, 4, 9, 16
3) 1/2, 1/3, 1/4, 1/5
4) 4x², 4x⁴, 4x6, 4x8
5) 120, 60, 30, 15​