The sum of the first n terms of an arithmetic progresssio...
The sum of the first n terms of an arithmetic progresssion is 252. If the first term is -16 and the last term is 72, find the number of terms in the series
6
7
8
9
Correct answer is D
Sn=252,a=−16andl=72Sn=n2(−16+72)252=n2(−16+72)n=50456n=9