Machine-translated by Google. Questions are authored in English.
Top

Discussion

How many values does \( \log z \) take for a given non-zero \( z \)?

  • A.finitely many, one for each quadrant
  • B.infinitely many, differing by multiples of \( 2\pi i \)
  • C.exactly two, differing in sign
  • D.exactly one, as in the real case

Answer: B

Writing \( z = re^{i\theta} \),

\[ \log z \;=\; \ln r + i(\theta + 2n\pi), \qquad n \in \mathbb{Z}, \]

so every choice of \( n \) gives a value. Restricting \( \theta \) to a range of width \( 2\pi \) picks the principal value, and the branch cut is where that restriction is imposed

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.