Find S10 for 2 + 5 +8 + ...  Please show your work.

Expert Answers

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This is regarding arithmetic series.

Common difference(d) = (5-2) = 3

Initial term(a) = 2

 

The sum of n terms in a arithmetic series is given by;

`S_n = n/2(2a+(n-1)d)`

 

Therefore;

`S_10 = 10/2(2*2+(10-1)*3)`

       `= 5(4+27)`

       `= 155`

 

So ` S_10 = 155`

Approved by eNotes Editorial Team
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