Question

12. If 5th and 6th terms of an A.P. are respectively
6 and 5, find the 11th term of the A.P.​

Answer 1

Answer:

T11 = 0

Step-by-step explanation:

Tn =a + (n − 1)d

T5 = a + (5 − 1)d = a + 4d

⇒T5 = a + 4d = 6........(1)

Similarly,

T6 = a + 5d = 5.......(2)

(2)-(1) gives

5d − 4d = 5 − 6 ⇒ d = −1

From (1)

a + 4d = 6 ⇒ a = 6 − 4(−1) = 10

Now,

T11 = 10 + (11 − 1)(−1)

=10 − 10

=0