GATE 2026 MA – Question 35
The series $\sum_{n=0}^\infty a_n(z-2)^n$ converges at z = 5 and diverges at z = −1. Find its radius of convergence (integer).
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Correct answer: 3 to 3
Explanation
Both points are distance 3 from the center 2. Convergence at one forces radius at least 3; divergence at the other forces it at most 3. Boundary behavior may differ, so both statements are consistent with **R = 3**.