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GATE 2024 MA – Question 12

Complex Analysis · Complex Integration and Residues · 1 mark · Multiple choice

C is the ellipse |z−2|+|z+2|=8 oriented counterclockwise. Evaluate $\oint_C z^2/(z^2-2z+2)\,dz$.

  1. 0
  2. $2\pi i$
  3. $4\pi i$
  4. $-\pi i$

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Correct answer: (C) $4\pi i$

Explanation

Poles 1±i lie inside the ellipse. Divide the integrand as $1+(2z-2)/(z^2-2z+2)$. The second term is the logarithmic derivative of a quadratic with two enclosed zeros; each has residue 1. Total integral is 2πi×2=**4πi, C**.

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