Question

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

Answer 1

Answer:

Step-by-step explanation:

a12=a +11d =-13 - (1)

S4 =4/2(2a+3d) =24

4a+6d=24

2a+3d = 12 -(2)

eq1×2 2a+22d=-26

eq2×1. 2a+3d= 12

__________

19d=-38

d=-2

Put it in eq (1)

a+11(-2) =-13

a-22=-13

a = 9

an10 =a+9d

=9 -18

= -18

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