Complex integration over a curve

In summary, the problem involves computing an integral over a positively orientated circle with the equation |z+2-i|=2. The center of the circle is at -2+i and the radius is 2. The equations for the circle can be written as z= -2+ i+ 2e^{i\theta}. The solver is unsure how to proceed with this center position and is seeking help to start the problem.
  • #1
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Homework Statement


Compute ∫C (z+i)/(z3+2z2) dz

Homework Equations


C is the positively orientated circle |z+2-i|=2


The Attempt at a Solution


I managed to solve a similar problem where the circle was simply |z|=1, with the centre at the origin converting it to z=e with 0≤θ2∏. I'm not sure how to go forward with the centre in another position.

If I want to parametise the equation for z for the circle, then I get two different equations for z because of the possibility that it could be + or - because of the absolute value.

I haven't gotten very far - could anyone help start me off on this!
 
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  • #2
|z+ 2- i|= 2 is the same as |z- (-2+ i)|= 2 and is the circle with center at -2+ i and radius 2 with [itex]\theta[/itex] going from 0 to [itex]2\pi[/itex]. Yes, we can write the circle with center at 0 and radius 1 as [itex]z= e^{i\theta}[/itex]. The circle with center at 0 and radius 2 is [itex]z= 2e^{i\theta}[/itex]. Finally, the circle with center -2+ i and radius 2 is [itex]z= -2+ i+ 2e^{i\theta}[/itex]
 
  • #3
Thank you, that helps!
 

Related to Complex integration over a curve

1. What is complex integration over a curve?

Complex integration over a curve is a mathematical concept that involves calculating the integral of a complex-valued function over a given curve in the complex plane.

2. What is the importance of complex integration over a curve?

Complex integration over a curve is important in many areas of mathematics and physics, such as in complex analysis, differential geometry, and quantum mechanics. It allows us to find important properties of a function, such as its derivatives and extrema, and also has applications in engineering and finance.

3. How is complex integration over a curve different from real integration?

Complex integration over a curve differs from real integration in several ways. Firstly, the domain of integration is a curve rather than a line segment or interval. Additionally, the integrand is a complex-valued function rather than a real-valued function. Finally, the techniques used to calculate complex integrals are different from those used in real integration, such as the Cauchy-Riemann equations and the residue theorem.

4. What is the Cauchy's integral formula for complex integration over a curve?

The Cauchy's integral formula states that the value of a complex integral over a curve is equal to the value of the function at any point inside the curve multiplied by 2πi. This formula is useful for calculating complex integrals, especially those with singularities inside the curve.

5. How is the residue theorem used in complex integration over a curve?

The residue theorem is a powerful tool in complex integration over a curve. It allows us to calculate complex integrals by evaluating the residues of a function at its singularities inside the curve. This theorem is particularly useful for calculating complex integrals that would be difficult to evaluate using other methods.

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