Question

in an ap if the 12 term is -13 and the sum of its first four term is 24 find the first 10 term of the ap

Answer 1

Answer:

11, 9, 7, 5, 3, 1, -1, -3, -5, -7

Step-by-step explanation:

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

sum of first 4 terms = 24

S10 = 24

$\frac{4}{2} (2a + (4 - 1)d) = 24 \\ 2(2a + 3d) = 24 \\ 2a + 3d = 12\: \: \: \: equ(2)$

multiply equ (1) with 2

2a + 22d = -26 equ (3)

equ (3) - (2)

19d = - 38

d = -38/19

d = -2

13th term

a + 12(-2) = -13

a - 24 = -13

a = -13 + 24

a = 11

the 10 terms are

11, 9, 7, 5, 3, 1, -1, -3, -5, -7, -9, -11, -13