Sign of u and v in a complex variable

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SUMMARY

The discussion focuses on determining the signs of u and v in the context of the complex square root function, where z = x + iy and sqrt(z) = u + iv. The derived formulas for u and v are u = ±(1/√2)√(x + √(x² + y²)) and v = ±(1/√2)√(-x + √(x² + y²)). The correct choice of signs is crucial for ensuring the proper representation of the complex square root, which involves equating the real and imaginary parts after squaring the equation.

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Fixxxer125
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Homework Statement


if z=x+iy and sqrt(z) = u+iv

u=±(1/√2)*√(x+√(x^2+y^2 ))
v=±(1/√2)*√(-x+√(x^2+y^2 ))
How must the signs on these result be chosen?

2. The attempt at a solution
I wondered if it was something to do with ensuring √(z) was always positive, but then ruled this out as it is a complex function. I don't really know where to do with this one! Thanks for your help
 
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Hi Fixxxer125! :smile:
Fixxxer125 said:
if z=x+iy and sqrt(z) = u+iv …

Do the obvious …

square the second equation: x + iy = z = (u + iv)2,

then equate real and imaginary parts (separately). :wink:
 
Ah brilliant, thanks!
 

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