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13. Find the sum of the first 15 multiples of 8. |
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Answer» Step-by-step explanation: The first 8 multiples of 8 are 8,16,24,32,40,48.56,64... These are in an A.P.having first TERM as 8 and common difference as 8 Therefore a=8 d=8 S15=? Sn=n/2 (2a+ (n-1)d) S15=15/2 (2(8)+ (15-1)8) 15/2(6+(14)(8)) 15 (128)/2 15×64=960...... hope it helps U.... Mark me as brainalist...... |
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