Convergence of Taylor Series for Various Functions

Berdi
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Homework Statement



For what values of x (or \theta or u as appropriate) do you expect the following Taylor Series to converge? DO NOT work out the series.

\sqrt{x^{2}-x-2} about x = 1/3

sin(1-\theta^{2}) about \theta = 0


tanh (u) about u =1


Homework Equations





The Attempt at a Solution



I'm not to sure where to begin. Taylor series have a radius of convergence where |x-a|< R, wher a is the nearest singularity, so I suppose that's a starting point?
 
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For what domain is \sqrt{x^{2}-x-2} defined? It can't converge beyond that.
 
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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