Question

If the 12th term of an ap is -13 and the sum of first four terms is 24 what is the sum of first 10 terms.?​

Answer 1

Answer:

The sum of first ten terms is 0.

Step-by-step explanation:

The 12th term of an AP is -13.

So,a+11d = -13

a= -13 - 11d

The sum of first four terms is 24.

So, 24= 4/2[2a+3d]

12 = 2a + 3d

12 = 2(-13-11d)+3d

12= -26 - 22d+3d

38 = -19d

d = -2

Put d value in a+11d = -13

So, a + 11(-2)= -13

a= -13+22

a = 9

a= 9 and d =-2

So,the sum of first ten terms is

S10 = 10/2[2(9)+(10-1)(-2)]

= 5(18-18)

= 0

The sum of first ten terms is 0.