Question

if the 10th term of an AP is 1 and 28th term is -5 find the AP​

Answer 1

Answer:

AP : 4 , 11/3 , 10/3 , 3 , 8/3 , 7/3 ,...,

Step-by-step explanation:

a10= 1, a28 = -5

a10 = a + 9d

1. = a + 9d - eqn 1

a28 = a + 27d

-5 = a + 27d. - eqn 2

solving eqn 1 and 2

a +9d = 1

a + 27d = -5

(-). (-). (+)

_____________

- 18d = 6

d = 6/(-18)

d = -1/3

Substitute d= -1/3 in eqn 1

a + 9d = 1

a + 9 (-1/3) = 1

a + 3(-1) = 1

a - 3 = 1

a = 1+3

a = 4

Therefore the required AP is 4 , 11/3 , 10/3 , 3 , 8/3 , 7/3 , ......