Complex integral question

The singular points are all at |z|=3, but since there is no z^-1 term in the series, the coefficient is zero and the residue at infinity is also zero. Overall, the integral evaluates to zero.
  • #1
nhrock3
415
0
[tex]\int_{|z|=3}^{nothing}\frac{dz}{z^3(z^{10}-2)}\\[/tex]
[tex]f=\frac{1}{z^3(z^{10}-2)}\\[/tex]
[tex]f(\frac{1}{z})=\frac{1}{(\frac{1}{z})^3((\frac{1}{z})^{10}-2)}\frac{z^{13}}{1-2z^{10}}=\\[/tex]
[tex]res(f,\infty)= res(\frac{1}{z^2}f(\frac{1}{z}),0)=\frac{1}{z^2}\sum_{n=0}^{\infty}(2z^{10})^n\\[/tex]
[tex]res(f,\infty)= res(\frac{1}{z^2}f(\frac{1}{z}),0)=-[res(f,inside|z|=3)+res(f,outside|z|=3)][/tex]

from the sum i get that there is no [tex]z^{-1}[/tex] member in the series
so the coefficient of [tex]z^{-1}[/tex] is zero

so the residiu of infinity is zero
but still all of my singular points are |z|=3
so the integral equals zero
??

did i solved it correctly
did i written every formula regarding the laws of residue correctly here
?
 
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  • #2
Yes, you solved it correctly. The formula for the residue of a function is correct and the result is that the integral is equal to zero since the residue at infinity is zero.
 

What is a complex integral?

A complex integral is an extension of the concept of integration from real numbers to complex numbers. It calculates the area under a curve in the complex plane, using a path instead of a single point.

What is the difference between a complex integral and a real integral?

A complex integral involves integrating functions with complex-valued inputs and outputs, while a real integral only deals with real numbers. Additionally, the path of integration in a complex integral can be any curve in the complex plane, whereas in a real integral it is limited to a line segment.

Why are complex integrals important?

Complex integrals are important in many areas of mathematics and physics, such as complex analysis, differential equations, and electromagnetism. They allow for the calculation of quantities that cannot be found using real integrals, and they have numerous applications in engineering and science.

How do you solve a complex integral?

Solving a complex integral involves finding an antiderivative of the complex function being integrated, and then evaluating the integral using the Fundamental Theorem of Calculus. This can be done analytically or numerically using various techniques such as the Cauchy integral theorem or contour integration.

What are some common applications of complex integrals?

Complex integrals have many applications in engineering and physics, such as calculating electric fields and potentials in electromagnetism, solving certain types of differential equations, and analyzing the behavior of functions in the complex plane. They are also used in signal processing, control theory, and image processing.

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