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In an A. P 8,11,14,... Find Sn-Sn-1 |
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Answer» In this AP a=8and d=11-8=3Sn=n/2[2a+(n-1)d] =n/2[2x8+(n-1)3] =n/2 [16+(n-1)3]Replace n by n-1Sn-1=n-1/2[2x8+(n-1-1)3] =n-1/2[16+(n-2)3]Now Sn-Sn-1=n/2[16+(n-1)3]-n-1/2[+(n-2)3] Now on solving you will get the answer hope it will help you thanks Vnnk |
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