Math, asked by ayusharrawatia276, 10 months ago

find the 31st term of an ap if the 3rd term is 4 and 9th term is -8 which term of A.P is zero

Answers

Answered by bktbunu
0

Answer:

31st term = -52

5th term = 0

Although without any proof we can get that 31st term = -52 and 5th term = 0, but we need to find the results by generalized process as follows.

Step-by-step explanation:

3rd term = 4

9th term = -8

number of terms between the 3rd term and 9th term = n = (9-3)-1 = 5

common difference = d = (9th term - 3rd term)/(n+1) = (-8-4)/6 = -12/6 = -2

1st term = a = (3rd term - 2d) = 4 - 2×(-2) = 4 + 4 = 8

31st term = a + (31-1)×d = 8 + 30×(-2) = 8 - 60 = -52

let nth term = 0

=> a + (n-1)×d = 0

=> 8 + (n-1)×(-2) = 0

=> 8 -2n + 2 = 0

=> 2n = 10

=> n = 10/2 = 5

Similar questions