Question

The 9th term of an A.P. is 449 and 449th term is 9. The term which is equal to zero is
A. 501th
B. 502th
C. 508th
D. none of these

Answer 1

D. none of these

Step-by-step explanation:

Given:  9th term of an A.P. is 449 and 449th term is 9

Find: term which is equal to zero

Solution:

   a9 = a + 8d   = 449 -----------(1)

 a449 = a + 448d = 9 -----------(2)

Subtracting (2) from (1), we get: -440d = 440

Therefore d = -1

Substituting d in (1), we get a - 8 = 449

Therefore a = 457.

Now Nth term = 0

 an = a + (n-1)d = 0

  n-1 = -a/d

  n = (1-a/d)

    = 1 - (457)/(-1)

    = 1 + 457

    = 458

458th term is zero. So Option D is the answer.