Question

Which term of A.P. 7 + 10 + 13 + .... is 109?

विकल्प

• 34th

• 35th

• 36th

• 37th

Answer 1

35th

Explanation:

a = 7

d = 10 − 7

= 3

a_n = 109

a_n = a + (n − 1)d

109 = 7 + (n − 1)3

109 − 7 = (n − 1)3

102 = (n − 1)3

`102/3` = (n − 1)

34 = n − 1

34 + 1 = n

n = 35