1.

If the nth term of the A.P. 9, 7, 5, ...... is same as the nth term of the A.P. 15, 12, 9, ...... find n.

Answer»

A = 9, D = 7- 9 = - 2

a = 15, d = - 3

An = an

A+(n - 1)D = a +(n -1)d

9 – (n -1)2 = 15 – (n -1)3

(n -1)(3 - 2) = 6

n - 1 = 6

n = 7



Discussion

No Comment Found