how many terms of the AP - 15 - 13 - 11 must be taken to give us some of minus 55 explain the reason for double answer
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Given, a=-15 d=2 Sn=-55
We know that, Sn=n/2 (2a+(n-1))
Subs.
-55=n/2 (-30+(n-1) 2)
Therefore, n=5. Or n=11
There are double answers because some values of the A. P may be negative while some may be positive which may result in the cancelation of certain values and hence we have doubke answers.
We know that, Sn=n/2 (2a+(n-1))
Subs.
-55=n/2 (-30+(n-1) 2)
Therefore, n=5. Or n=11
There are double answers because some values of the A. P may be negative while some may be positive which may result in the cancelation of certain values and hence we have doubke answers.
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therefore we have double answers.
hope it helps
hope it helps
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