Question

In an A.P., the first term is 2, the last term is 29 and the sum of the terms is 155. Find the common difference of the A.P.

Answer 1

Answer:

use formula Sn = n/2(a+tn) and tn = a+(n-1)d

Answer 2

    d = +3

Step-by-step explanation:

(i) Given: In an A.P., the first term is 2, the last term is 29 and the sum of the terms is 155.

Find: d

  a = 2

  Sum = 155

  an = 29 = a + (n-1)d

  So 2a + (n-1)d = an + a = 29 + 2 = +31

  Now Sum = n/2 (2a + (n-1)d)

  155 = n/2 (31)

  n = 155 *2 / 31

  n = 10

  Substituting n in an, we get: 2 + 9d = 29

   9d = 27

    d = +3

  AP will be 2, 5, 8,........26, 29.