Question

1,Find the eighth term of the geometric sequence whose 1st term is 5 and whose 4th term is

1/25.​

Answer 1

Solution will be 1/15625

Explanation:

Substitute the value of first term for ar^(4-1) for the third term with 1/25 on RHS, make r the subject (which is the common ratio)

you'll get r as 1/5

Now for the eighth term, replace the "4" in the formula with "8" and a with "5" and observe the magic.