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z is element of IC:

Re((z-1)/(z-i))>=2

find all values for z

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 Apr 9, 2016
 #1
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This is what Wolfram/Alpha computing engine says about your problem:

 

"inequalities are not well-defined in the complex plane (the field of complex numbers is not totally-ordered)"

 Apr 9, 2016
 #2
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If we set z = a + bi, where a and b are Real, then the blue surface in the 3d graph below shows where the valid parameters lie.

 

3d

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 Apr 9, 2016
 #3
avatar+33661 
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By setting (a^2 + b^2 - a - b) = 2(a^2 + b^2 - 2b + 1)  we find that the boundary within which Re((z-1)/(z-i))>=2 is given by 

 

(a + 1/2)^2 + (b - 3)^2 = r^2  where r^2 = 33/4   This is a circle of radius ≈ 2.872, centred on (-1/2, 3).

 

Any combination of a and b such that (a + 1/2)^2 + (b - 3)^2 <= r^2  produces a value of z that satisfies Re((z-1)/(z-i))>=2

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 Apr 9, 2016

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