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Find the 11th partial sum of the summation of negative 7i plus 22, from i equals 1 to infinity.


∑ -7+22?
i=1

1 Answer

3 votes
I think you mean,


\sum_(i=1)^(\infty)(7i+22)

You can use the usual formula,


S_(k)=(k)/(2)(a_1+a_k)

That in this case is,


S_(11)=(11)/(2)(29+99)=704

Where I have used,


a_k=7\cdot k +22
User Johnjohn
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