SOLUTION: AnAP has 15 term and a common difference of -3 find the first and last term if its sum is 120
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Question 998907: AnAP has 15 term and a common difference of -3 find the first and last term if its sum is 120
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
n=15
a=?
d=-3
=(15/2)(2a-42)
120*2 = 15(2a-42)
120*2/15 = 2a-42
8*2=2a-42
16+42=2a
58=2a
a=29 First term
=29-41
=-12
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