Question

The sum of the first 10 terms of an A.P is 15, and the sum of the next 10 terms is 215. Find the A.P.

Answer 1

Step-by-step explanation:

given, s10 = 15

5[2a+9d] =15 (a is first term, dis c d)

2a+9d= 3 ----(1)

given sum of next ten term s = 215

so,sum of first 20 term s=215+15

= 230

10[2a+19d] = 230

2a+19d=23 -----(2)

from 1 &2

10d= 20

d=2

so, a= -7

so,A.P = -7,-5,-3,-1…