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Math Help - to prove f is constant

  1. #1
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    to prove f is constant

    Let f:C→C be differentiable, with f(z)/=0 (not equal) for all z in C. Suppose limz→z0 f(z) exist and is nonzero. Prove that f is constant.
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  2. #2
    Behold, the power of SARDINES!
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    Quote Originally Posted by AcCeylan View Post
    Let f:C→C be differentiable, with f(z)/=0 for all z\inC. Suppose limz\to z0 f(z) exist and is nonzero. Prove that f is constant.
    The statement is false consider the function

    f(z)=e^z \quad \lim_{z \to z_0}f(z)=e^{z_0} and this function is holomorphic, but is not constant.
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  3. #3
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    Yes you are true!!?? but I found this question in a complex analysis book, I tried to solve but I hadnt thought that it could be false..!!
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  4. #4
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    Can you get that f is an entire function whose image misses a neighborhood of zero? In that case, 1/f is a bounded entire function, and you can apply Liouville's.
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  5. #5
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    Take limit e^z as z→-infinity it equal to zero, so it not satisfy the statement. I proved this statement with using Liouville Theorem
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