What is the Substitution Method for Integrating a Rational Function?

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Homework Statement



∫1/(x^2+2x+2) dx


Homework Equations





The Attempt at a Solution



u = x^2+2x+2
du = 2dx(x+1)

But I am left with an x and can not find the antiderviative
 
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Try the substitution u = x+1.
 
Using the substitution suggested by Pengwuino, you should get
\int \frac{du}{u^2 + 1}

Hopefully you know an antiderivative for this integral.
 
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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