The sum of the first sixteen terms of an AP is 112 and the sum of its next fourteen terms is 518..Find the AP....

  • 20

 Let and d be the first term and common difference of A.P. respectively.

Given, S 10 = –150

Given, Sum of next 10 terms = a 11 + a 12 + a 13 + ... + a 20 = – 550

Solving (1) and (2), we get

When d = – 4, we get

2a + 9 � (– 4) = –30 (Using (1))

⇒ 2a = – 30 + 36 = 6

⇒ a = 3

Thus, the given A.P. is 3, –1, –5, –9, ...

  • -5
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