find the sum of first 15 terms of the AP 8, 7 1 by 4, 6 1 by 2,53 by4
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Answer:
n=15
a=8
d=71by4-8
=39by4
Sn=n\2[2a+(n-1)d]
=15/2[2×8+(15-1)39/4
=15/2[16+14×39/4]
=15/2[16+136.5]
=15/2×152.5
=7.5×152.5
=1143.75
Explanation:
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