SOLUTION: Find the sum in the series (15/42)+(15/56)+(15/72)+(15/90)+...+(15/9900)

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Question 1099656: Find the sum in the series (15/42)+(15/56)+(15/72)+(15/90)+...+(15/9900)
Found 2 solutions by richwmiller, ikleyn:
Answer by richwmiller(17219)   (Show Source): You can put this solution on YOUR website!

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Answer by ikleyn(52781)   (Show Source): You can put this solution on YOUR website!
.
 =  = .

 =  = .

 =  = .

 =  = .


All your terms are of the form 

 =      (if to forget about the common numerator "15" for a minute . . . )


the last term is

 =  .


Now, if to sum up all these lines, all internal terms will cancel each other, and the sum will be simply  .


Now recall about the numerator "15" and multiply by 15. You will get your


Answer.  The sum is equal to  .

         You can simplify it further, if you want.

Solved.



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