Rouche's Theorem: Find Zeros of f(z)=z^9-2z^6+z^2-8z-2 Inside Unit Circle

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SUMMARY

The discussion focuses on applying Rouche's Theorem to determine the number of zeros of the polynomial f(z) = z^9 - 2z^6 + z^2 - 8z - 2 within the unit circle. Participants suggest using g(z) = -8z as a candidate function for comparison, based on the principle of selecting the term with the highest coefficient. The condition |f(z) - g(z)| < |f(z)| must hold for all points on the contour defined by the unit circle to conclude that f and g share the same number of zeros inside this region.

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Homework Statement


Find the number of zeros of the folowing polynomial lying inside the unit circle,
f(z)= z^9 - 2z^6 + z^2 - 8z - 2



The Attempt at a Solution


Rouche's Theorem says if f and g differentiable which contains a simple loop s and all points inside s.
if |f(z)-g(z)|<|f(z)| for all z=s(t)
then f and g have same zeros inside s.

which g(z) should I choose, -2z^6, or z^2 or -8z
how can I determine?
 
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Try, -8z. In general, try the term with the highest coefficient...
 

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