Find where a complex function is differentiable

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SUMMARY

The function f(z) = Im(z)/z conjugate is not complex differentiable at any point in the complex plane. To demonstrate this, one must apply the definition of the derivative directly, rather than relying on the Cauchy-Riemann equations. By substituting z = x + iy, the function can be expressed as f(x + iy) = (y)/(x + iy) = (xy - iy^2)/(x^2 + y^2). Analyzing the real and imaginary components separately confirms the lack of differentiability.

PREREQUISITES
  • Understanding of complex functions
  • Familiarity with the definition of the derivative
  • Knowledge of real and imaginary parts of complex numbers
  • Basic grasp of complex conjugates
NEXT STEPS
  • Study the definition of complex differentiability in detail
  • Learn about the Cauchy-Riemann equations and their implications
  • Explore examples of complex functions that are differentiable
  • Investigate the geometric interpretation of complex derivatives
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Mathematics students, educators, and professionals in fields involving complex analysis who seek to deepen their understanding of differentiability in complex functions.

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Using the definition of the derivative find at which points the function f(z) = Im(z)/z conjugate is complex differentiable.
I know that it is not complex differentiable anywhere but I need to show it using the definition and not the Cauchy Riemann equations.
 
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Write z= x+ iy, so that f(z)= f(x+ iy)= \frac{y}{x+ iy}= \frac{xy- iy^2}{x^2+ y^2}[/tex] Apply the definition of "differentiable" to that. (It is sufficent to look at the real and complex parts separately.)
 

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