MCQ - 445-9177

Correct Answer: D

Explanation:

Let a be the first term and d be the common difference.
Given: a₇ = - 1
a₁₆ = 17
Now, Consider a₇ = - 1
⇒ a + 6d = - 1 …………(1)
Consider a₁₆ = 17
⇒ a + 15d = 17 …………(2)
Subtract equation (1) from (2), we get,
9d = 18
⇒ d = 2
∴ Common difference = d = 2
Now, from equation (1), we get,
a = - 1 - 6d
= - 1 - 6(2)
= - 13
Now, n^th term of the AP is given by
a_n = a + (n - 1)d
= - 13 + (n - 1)2
= 13 + 2n - 2
= 2n - 15