How many terms of the A.P. - 6, - 11/2, -5,....are needed to give the sum –25?

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asked Feb 10, 2018 in Mathematics by Rohit Singh (61,782 points) 35 133 355
How many terms of the A.P. - 6, - 11/2, -5,....are needed to give the sum –25?

1 Answer

+1 vote
answered Feb 10, 2018 by sameer (82,980 points) 5 11 37
selected Feb 14, 2018 by sanjeev
 
Best answer

Let the sum of n terms of the given A.P. be –25.
It is known that,

Where n = number of terms, a = first term, and d = common difference
Here, a = –6

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