Question

How many terms of the AP:-15,-13,-11...Are needed to make sum -55?Explain the reason for double answer.
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Answer 1

Answer:

Now, the common difference of the AP is the difference between the first and second term. We are also given that the sum of the AP is 55. Let n terms be used to make the sum 55. Therefore, the number of terms needed to make the sum 55 are 5 or 11.