For the AP - 3, - 7, - 11, … can we find directly a30 - a20 without actually finding a30 and a20 reason for your answer.
True
Given
First term, a = - 3
Common difference, d = a2 - a1 = - 7 - (- 3) = - 4
a30 - a20 = a + 29d - (a + 19d)
= 10d
= - 40
It is so because difference between any two terms of an AP is proportional to common difference of that AP