Question

if 10th term of an Ap is -25 and 17th term is - 46 find the ap​

Answer 1

Answer:

T10 = -25

a+9d = -25,

a= -25-9d

Similarly

a+16d = -46

-25-9d+16d=-46

7d = -21

d = -3

Answer 2

Answer:

AP = 52, 49, 46, 43

Step-by-step explanation:

let the 1st term of AP be a

and the common difference be d

given,

10th term of an Ap is -25

so,

a + (10 - 1)d = -25

a + 9d = -25. ...(1)

also,

17th term is - 46

so,

a + (17 - 1)d = -46

a + 16d = -46. ...(2)

(1) - (2)

a + 9d - (a + 16d) = -25 - (-46)

a + 9d - a - 16d = -25 + 46

9d - 16d = 21

-7d = 21

d = 21/-7

d = -3

putting the value of d on (1)

a + 9d = -25

a + 9(-3) = 25

a - 27 = 25

a = 25 + 27

a = 52

so,

AP = a, a + d, a + 2d, a + 3d

52, 52 + (-3), 52 + 2(-3), 52 + 3(-3)

52, 52 - 3 , 52 - 6, 52 - 9

52, 49, 46, 43

so,

AP = 52, 49, 46, 43