Question

The first term of an AP is-8. The ratio of the 7th term to the 9th term is 5:8. Calculate the common difference of the progression.

Answer 1

a = -8
(a+6d)/(a+8d) = 5/8

So, plug in a and solve for d:

(6d-8)/(8d-8) = 5/8
...

Answer 2

The first term of an arithmetic sequence is -1and the first fifteenth ters is 27 find the common difference and the sum of the first fifteen terms