Question

In an ap if 12th term is -13 and the sum of its first four terms is 24 .Find the sum of first 10 terms

Answer 1

Answer:

Step-by-step explanation:

a12 = -13

a+11d= -13__________ 1)

a+a+d+a+2d+a+3d = 24

4a + 6d = 24________2)

solve 2 and  1 equation

then find a and d

substitute by putting sum formula

Answer 2

a+11d= -13

a= -13-11d ------> (1)

4/2(2a+(4-1)d)= 24

2a+3d= 12 ------> (2)

Substituiting (1) in (2)

d= -2

a= 9

Sum of first 10 terms = 10/2(18-18)

= 0