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

Discussion

What kind of singularity does \( \dfrac{\sin z}{z} \) have at the origin?

  • A.essential
  • B.removable
  • C.a simple pole
  • D.a pole of order two

Answer: B

Expanding the numerator and dividing,

\[ \frac{\sin z}{z} \;=\; \frac{z - z^{3}/6 + \cdots}{z} \;=\; 1 - \frac{z^{2}}{6} + \cdots, \]

a series with no negative powers at all. The limit is one, so assigning that value at the origin makes the function analytic there. The zero of the numerator cancels the zero of the denominator

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

Post your comment

Please log in or register to post a comment.