find the sum of first 5 multiplies of 8
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Step-by-step explanation:
The multiplies of 8 are 8,16, 24,32......
These are in an A. P., haveing 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(16+(14)8)
=15*128/2
=960
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