Question

Two A.P's have the same common difference.If the difference between their 20^th terms is 30, find the difference between their 30^th terms

Answer 1

Since their common difference is the same , the difference between their 30th term will also be 30.

Let the first terms of the two APs be A1 and a1.
(20th term= a+19d)

Here both APs have same common difference.
So difference between 20th term= ((A1+19d)-(a1+19d)) = A1-a1
=30

So difference between 30th term= ((A1+29d)-(a1+29d))
= A1-a1
=30