How Do Complex Plane Transformations Affect Equations?

[nokia8650]

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Above is the problem and given solution. I am unable to understand the solution for part b - if x =4 then surely u/(u^2 + v^2) =4. Can someone please clarify this.

Thanks in advance.

 

[Hao]

Typo is the only thing that comes to mind.

I think it should be 4.