InterviewSolution
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InterviewSolution
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Can you explain sum of first n terms of an AP |
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Answer» Thanks Let Sn be the sum of n terms with \'a\' first step and \'d\' is common differencethen Sn= a + (a+d )+ ................+a+(n-2)*d.+a+(n-1)*dor Sn=(a+(n-1)*d).+(a+(n-2)*d ) ............+(a+d ) + a ( Taking Last term first)2Sn=2a +(n-1)*d +(a+d +a +(n-2)*d +...........\xa02Sn=(a+a +(n-1)*d )+(a+a +(n-1)*d +...........n terms2Sn= n*(a+a +(n-1)*d )Sn=n*(2a +(n-1)*d ) / 2 Aaa |
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