Question

2. The 12th term of a series in A.P. is –13 and the sum of the first four terms of it is 24. Find the sum of its first ten terms.

Answer 1

0 is the answer
first find the first term and the common difference then solve it further

Answer 2

Given, a +11d=-13
S4=4/2(2a+3d)
24=2(2a+3d)
12=2a +3d
Multiplying a+11d=-13 with 2,
-26=2a+22d
Solving the equations we get,
38=-19d
d=-2
a-22=-13
a=9
S10=10/2(2*9+9*-2)
S10=5*0=0
So, the sum of its first 10 terms is 0.