Sunday, 31 May 2015

algebra precalculus - Sum of series: 13(22)+24(32)+35(42)+dots?

I am trying to find the sum of the above series.



The sum till n terms can be found using power series expansion. However, I'm trying to solve this using the method of difference (a.k.a. Telescoping sum or Vn method).



In this method, the general term is expressed as the difference between two consecutive values of some function. Like the following:




Tn=VnVn1



and then the sum is taken which comes to be



Sn=VnV0



The general term of the series in question can be represented as a product:



Tn=n(n+1)2(n+2)




But I am unable to represent this as a difference. How can I proceed from here to find the sum?

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