SOLUTION: Find the sum of the first 12 terms of the arithmetic sequence whos general term is an=3n+ 5

Question 976296: Find the sum of the first 12 terms of the arithmetic sequence whos general term is an=3n+ 5

Answer by dkppathak(439) (Show Source): You can put this solution on YOUR website!
Find the sum of the first 12 terms of the arithmetic sequence whose general term is an=3n+ 5
a1=3x1+5=8
a2=3x2+5=11
a3=3x3+5=14
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.
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a12=3x12+5=41
therefor it will be AP whose 12 therms are as 8,11,14,--------41
a=8 d=3 n=12 l=41
sn=n(a+l)/2=12(8+41)/2=12x49/2=6x49=294
sum of 12 terms is 294
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