The sum of the first 7 terms of an A.P. is 10, and that of the next 7 terms is 17. Find the progression
Assuming the first term as a and common difference as d
To find: the progression
So, the sum of first 7 terms is given by
a + a + d + a + 2d + a + 3d…. a + 6d = 10
7a + 21d = 10…(i)
In the second part it is given that sum of next seven terms is 17
a + 7d + a + 8d + a + 9d…. a + 13d = 7
7a + 70d = 7…(ii)
Solving (i) and (ii) we get
10 - 21d = 7 - 70d
3 = - 49d
Hence the sequence is given by a, a + d, a + 2d…. which is