Find the common difference of an AP whose first term is 5 and the sum of its first four terms is half the sum of the next four terms.
Given a = 5,
Sum of n terms, Sn=n2[2a+(n−1)d]
Sum of first n terms, S4=42[2×5+(4−1)d]
Sum of next 4 terms =S8−S4
According to the question,
Common difference = 2