Question Detail
Question
How many terms of the AP 17, 15, 13, ... must be added to yield a sum of 72?
Correct Answer
Option A is the correct answer.
Detailed Explanation
S_n = (n/2)[34 + (n - 1)(-2)] = n(18 - n) = 72, which gives n^2 - 18n + 72 = 0. Factoring yields (n - 6)(n - 12) = 0, so n = 6 or 12.
Hint
No hint available