find the sum of n term of the series 2.5 + 5.8 + 8.11 +...
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HEY !! HERE IS YOUR REQUIRED ANSWER STEPWISE-:
The First sequence in the series is 2+5+8+…n terms
This is an A.P. with first term as 2 and common difference 3.
∴T¹ =2+3(n−1)=3n−1
The Second sequence in the series is 5+8+11…n terms
This is an A.P. with first term as 5 and common difference 3
∴T² =5+3(n−1)=3n+2
Thus n term of the series =(3n−1) (3n+2) = 9n² + 3n - 2
Therefore, Sn = ∑(9n² + 3n - 2 =
= 3n² ( n + 1 )
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