Question

Write an equation for the nth term of the geometric sequence 5,20,80,320...

Answer 1

5,20,80,320

Your input appears to be an geometric series.

Find the ratio (r) between adjacent membersa2/a1=20/5=4a3/a2=80/20=4a4/a3=320/80=4

The ration (r) between every two adjacent members of the series is constant and equal to 4

General Form: an=a1×rn-1This geometric series: an=5×4n-1