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Without adding, find the sum of: 1 + 3 + 5 + 7 + 9 + 11 +13+15+17 |
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Answer» Step-by-step EXPLANATION: a=1 an or l=17 d=3-1=2 an=a+(n-1)d 17=1+(n-1)2 16/2=n-1 8=n-1 n=9 sn=n/2 X (a+l) =9/2 x (1+17) =9/2 x 18 =9 x 9 =81 |
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