Question

The sum of first 20 numbers in an



a.P. Is equal to the sum of first 30 numbers. Find the sum of first 50 numbers of the



a.P.?

Answer 1

$<b>$ solution :-

Sum = (n/2)(2a + (n - 1)d)

(20/2)(2a + 19d)= (30/2)(2a + 29d)

20a + 190d = 30a + 435d

10a = - 245d

a =( - 49/2) d

Sum of 50 first terms = 25(-49d +49d)=0

Answer -50 terms of Ap is 0