Using Cauchy's integral formula to evaluate integrals

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The integral of (z/(z+9)^2)dz along the contour γ(t) can be evaluated using Cauchy's integral formula. Since the function is holomorphic within the circle defined by γ(t), and the singularity at -9 lies outside this contour, the integral evaluates to zero according to Cauchy's theorem. Participants agree that the integral's value is indeed zero due to these conditions. This confirms the application of Cauchy's theorem in this context. The discussion emphasizes the importance of identifying singularities relative to the contour in complex analysis.
Woolyabyss
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Homework Statement


Use Cauchy’s integral formula to evaluate the integral along γ(t) of (z/(z+9)^2)dz
where γ(t) = 2i + 4e^it , 0 ≤ t ≤ 2π.

Homework Equations


Cauchy's integral formula

The Attempt at a Solution


I was just wondering is the integral not just zero by Cauchy's theorem since (z/(z+9)^2) is holomorphic inside the circle defined by γ(t) ( the singularity at -9 is outside the circle ).
 
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Woolyabyss said:

Homework Statement


Use Cauchy’s integral formula to evaluate the integral along γ(t) of (z/(z+9)^2)dz
where γ(t) = 2i + 4e^it , 0 ≤ t ≤ 2π.

Homework Equations


Cauchy's integral formula

The Attempt at a Solution


I was just wondering is the integral not just zero by Cauchy's theorem since (z/(z+9)^2) is holomorphic inside the circle defined by γ(t) ( the singularity at -9 is outside the circle ).
Yes, that seems to be the case.
 
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Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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