Solve Equation for x: R= ((a^-x)-(b^-x))/((c^-x)-(a^-x))

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Homework Statement


To solve the following equation for x in terms of R and 3 constants a,b, and c:

R = ((a^-x)-(b^-x))/((c^-x)-(a^-x))

Homework Equations



Just the given equation

The Attempt at a Solution



I have tried taking the natural log of both sides but that doesn't seem to get me anywhere. Any suggestions?
 
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Your equation can be rewritten as
R = \frac{1/a^x - 1/b^x}{1/c^x - 1/a^x}

I would start with combining the two expressions in the numerator and the two in the denominator and simplify, then see where that takes me.
 
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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