Q8 of 167 Page 20

Mark the correct alternative in the following:

If the sum of n terms of an A.P., is 3 which of its terms is 164?


Here, Sn=3n2+5n


∴ S1=3+5=8


∴ a1=S1=8


And S2=3×22+5×2=22


Now,a2=S2-S1=22-8=14


∴ d=a2-a1=14-8=6


Now, an=a1+(n-1)d


∴ 164=8+(n-1)6


∴ 156=(n-1)6


∴ 26=n-1


∴ n=27

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