Singularity and residue theorem

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The discussion focuses on finding the singularity and residue of the function f(z) = e^(-2z) / (z + 1)^2. The user correctly identifies the singularity at z = -1 and calculates the residue using the limit of the derivative. The residue is determined to be -2e^2, which is confirmed by a check with Mathematica. The conversation highlights the importance of verifying calculations in complex analysis. Overall, the user successfully demonstrates understanding of singularities and residues.
MissP.25_5
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Hello.
Can someone check if I got the answer right?

Find the singularity and the residue.

##f(z)=\frac{e^{-2z}}{(z+1)^2}##

My solution:

##f(z)=\frac{e^{-2z}}{(z+1)^2}##
$$Resf(z)_{|z=-1|}=\lim_{{z}\to{-1}}\frac{d}{dz}((z+1)^2\frac{e^{-2z}}{(z+1)^2})$$

$$\lim_{{z}\to{-1}}-2e^{-2z}=-2e^{2}$$
 

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A check with Mathematica tells me that your solution is correct :-).
 
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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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