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Find the residues of the following functions at the indicated points. Try to select the easiest of the methods outlined above. Check your results by computer.

eiz9z2+4atz=2i3

Short Answer

Expert verified

Hence, the residue of the function at z0=2i3 is -0.042785i.

Step by step solution

01

Given information

The given function is: fz=eiz9z2+4.

02

Residue Theorem

If z0 is an isolated singular point of f(z) . Then the integration of the function within any closed curve C is given by:

∮cfzdz=b1·2πi

Here, b1 is the residue.

03

Find the Residue

As we know, the residue of the function is given by:

Rz=z0=gz0h'z0, for fz=gzhz

According to the question, we have:

gz=eizhz=9z2+4⇒h'z=18z

Now, the residue atz0=2i3 will be:

R2i3=g2i3h'2i3=ei·2i3182i3=e-2312i=-ie-2312=-0.042785i

Hence, the residue of the function at z0=2i3 is -0.042785i.

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