Finding Value of \sum_{i=1}^{n}: Intro to Integration

mateomy
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We're going over the intro stuff to integration and we are being asked to find the value of the sums...

Here's the problem I am getting stuck on...

<br /> \sum_{i=1}^{n} (i^2 + 3i + 4)<br />

I know that I have to separate the individual sums, so I put it into this form...

<br /> \sum_{i=1}^{n} i^2 + 3\sum_{i=1}^{n} i + \sum_{i=1}^{n} 4<br />

And then I know the individual forms of the Riemann sums of i^2 and i, etc.

<br /> \sum_{i=1}^{n} i^2 = \frac{n(n+1)(2n+1)}{6} etc, etc...<br />

am I just adding these together as if they were fractions (finding common denominators, etc)?
 
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Yes, you could just put them together like fractions.
 
Awesome, thanks.
 
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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