Find the explicit formula that produces the given sequence

Question

-2/25,-2/25 ,-2/5,-2 

 

Answer 1

-2/125, -2/25, -2/5, -2 is a geometric sequence with common ratio r = 5

each term is 5 times the previous term

first term is -2/125

the nth term = a1r^n-1 where a1 = first term and r = the common ratio

1st term = a1r^n-1 = -2/125(5^1-1) = -2/125(1) = -2/125

4th term = a1r^(4-1) = -2/125(5^3) = -2