Expressing a Sum in Sigma Notation: 1 + (2/3) + (3/5) + (4/7) + (5/9)

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Homework Statement



"Express the following sum in sigma notation:

1 + (2/3) + (3/5) + (4/7) + (5/9)"

Homework Equations





The Attempt at a Solution



I've figured out what they all have in common (1+2=3, 2+3=5, 3+4=7, 4+5=9) but I've been searching through the book and on the internet how to express this.
 
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Suppose the kth term is n(k)/d(k). Can you find a pattern to how the numerator and denominator change with k?
 
I just figured it out. Apparently I just needed to finally ask for help.

The equation is (i/2i-1) with start i=1 and end at 5.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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