Question

Find an equation for the nth term of a geometric sequence where the second and fifth terms are -2 and 16, respectively.

Answer 1

a geometric sequence has terms a , ar, ar^2, ar^3..
where a = first term and r = common ratio

so with this GS second term = ar = -2
and fifth term = ar^4 = 16

can you see how you can find r from these 2 equations?

Answer 2

try dividing