How to Evaluate the Integral of dz/(2+z*) for C Given by z=1?

In summary, to evaluate the given integral of a closed curve with a given parameter z=1, we can use Cauchy's integral formula. However, since z* is not an analytic function of z, we need to find an analytic expression for z* in terms of z, which is only valid on the unit circle. This can be achieved by considering the expressions of z and z* in polar coordinates.
  • #1
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Homework Statement


evaluate :

integral of closed curve dz/(2+z*) (sorry for the lack of syntax
where C is given by z=1


Homework Equations



Cauchy's integral formula

The Attempt at a Solution


I believe I have to change the denominator in terms of z rather than z*, but I do not know how. Any help?
 
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  • #2
z* is not an analytic function of z, however if z is on the unit circle, then you can find a suitable analytic expression for z* in terms of z (which is then only valid on the unit circle).

Hint: consider the expressions of z and z* in polar coordinates.
 

FAQ: How to Evaluate the Integral of dz/(2+z*) for C Given by z=1?

What is Cauchy's Integral Formula?

Cauchy's Integral Formula is a theorem in complex analysis that relates the values of a holomorphic function inside a closed contour to the values of the function on the boundary of the contour. It is named after the French mathematician Augustin-Louis Cauchy.

What is a holomorphic function?

A holomorphic function is a complex-valued function that is differentiable at every point in its domain. This means that the function is smooth and has no sharp corners or breaks. In other words, it is a function that can be represented as a power series.

How is Cauchy's Integral Formula used?

Cauchy's Integral Formula is used to calculate the values of a holomorphic function at any point within a closed contour, given the values of the function on the boundary of the contour. It is a powerful tool in complex analysis and has applications in various areas of mathematics and physics.

What is the relationship between Cauchy's Integral Formula and the Cauchy-Riemann equations?

The Cauchy-Riemann equations are a set of necessary and sufficient conditions for a complex-valued function to be holomorphic. Cauchy's Integral Formula is a consequence of these equations and can be used to prove the analyticity of a function.

Can Cauchy's Integral Formula be extended to functions with singularities?

Yes, Cauchy's Integral Formula can be extended to functions with singularities, but the contour of integration must be modified to avoid the singular points. This extension is known as the Cauchy integral theorem and is an important tool in the study of complex analysis.

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