How to Calculate Contour Integrals Using the Given Property?

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Discussion Overview

The discussion revolves around calculating contour integrals using a specific property, particularly focusing on the integral of the function \( \frac{1}{z^2 - i} \) over a circular contour defined by \( |z| = 3 \). Participants are exploring the implications of the property \( | \int_C f(z) dz | \leq ML \) in this context.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant expresses difficulty in understanding the property and seeks clarification on the meaning of "ML".
  • Another participant suggests that "ML" likely refers to two constants, M and L, and proposes starting by factoring the denominator and identifying poles of the integrand.
  • A different participant clarifies that M represents the upper bound of \( |f(z)| \) on the contour C, while L is the arc length of the contour.
  • One participant references a mathematical inequality related to integrals, indicating a method to approach the problem.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the interpretation of "ML" and its components, but there is a general agreement on the importance of identifying poles and understanding the bounds of the function involved.

Contextual Notes

There are unresolved assumptions regarding the definitions of M and L, as well as the specific steps needed to prove the inequality related to the contour integral.

cateater2000
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Hi, I'm having a bit of trouble with this question.

Use the property |integral over c of f(z)dz|<=ML
to show |integral over c of 1/(z^2-i) dz|<=3pi/4

where c is the circle |z|=3 traversed once counterclockwise


thanks in advance for any tips.
 
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I'm not sure what "ML" means, though presumably it is a constant. Is the "L" a subscript by chance?

At any rate, a good start would be to factor the denominator of the integrand, and determine the poles. Once you have done that, ask yourself if the poles lie inside the circle |z|=3. That should get you well on the way to proving what you are asked to prove.
 
I think the ML
is M*L two different constants

I geuss I could do the pole thing, thanks for the reply.
 
I`m sure M means the upper bound of |f(z)| on C and L is the arc length of the contour C.

[tex]\left|\int_C f(z)dz\right|=\left|\int_a^bf(z(t))\frac{dz(t)}{dt}dt\right|[/tex].

Now use the fact that:
[tex]\left|\int_a^b f(t)dt\right|\leq \int_a^b \left|f(t)\right|dt[/tex]
 

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