Find the common difference of an A.P. Whose first term is 5 and the sum of its first four terms is half the sum of the next four terms.
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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
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
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