Deriving the Integral via Leibniz Rule

dirk_mec1
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Homework Statement


<br /> \int_0^1\frac{x-1}{\ln{x}} dx<br />

Homework Equations


<br /> \Phi(\alpha)=\int_0^1\frac{x^{\alpha}-1}{\ln{x}} dx<br />

The Attempt at a Solution


In the answers they say:<br /> \Phi &#039;(\alpha)=\int_0^1\frac{x^{\alpha}\ln{x}}{\ln{x}} dx=\frac{1}{\alpha+1}<br />but the derative is wrong, right? I don't understand how they calculated the derative...
 
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The derivative is d/d(alpha). x^alpha=e^(log(x)*alpha). Actually, it is right.
 
Dick said:
The derivative is d/d(alpha). x^alpha=e^(log(x)*alpha). Actually, it is right.

You're right I accendentally differentiated w.r.t x, thanks Dick.
 
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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