Geometric reps of complex formula

wildman
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Homework Statement


Describe geometrically the sets of points determined by the relations:

a) |z-i|+|z-1| = 2
b) |z-i|=|z+1|
c) Re z = |z-2|

Homework Equations





The Attempt at a Solution



I know the answer of a is suppose to be Ellipse with foci at i and 1, major axis 2
and b is Perpendicular bisector of the line segment connecting z=i and z = -1
and c is Parabola focus at z=2, directrix the imaginary axis (from the back of the book), but could one of you help me to see how the author got those answers?
 
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The most direct way to handle all of them is to put z=x+iy and look at the x,y equations. You could also look up the geometric definition of an ellipse and a parabola to do those more directly.
 
Yep. The direct method worked. Thanks.
 
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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