Question

Find the comman difference of an AP whose first term is 5 and the sum of first four term is half the sum of next four terms

Answer 1

Let d is common difference of AP
now first 4term is 5,5+d,5+2d,5+3d
and next 4term 5+4d,5+5d,5+6d,5+7d
now according to question
20+6d=(20+22d)/2
20+6d=10+11d
d=2