The sum of first 10 terms of an AP is -150 and the sum of its next 10 terms is -550. Find the AP.
Let a be the first term and d be the common difference of the AP.
It is given that the sum of its next 10 terms is – 550
S20 = Sum of first 20 terms = Sum of first 10 terms + Sum of the next 10 terms = – 150 + (- 550 ) = -700
Subtracting (i) from (ii), we get
Putting d = -4 in (i), we get