Ramon’s teacher wrote the following table on the board

She then asked the class to write a rule for the nth term of the geometric sequence represented on the table, using the format an=a(r)^n-1

Select the values for a and r that Ramon should use in order to correctly write the rule for the nth term.

an= ___(___)^n-1

—> number choices
-3
-1/3
1/3
3
9
27
81

please only respond if you know the answer :)