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math121a-f23:hw_3 [2023/09/08 21:45]
pzhou
math121a-f23:hw_3 [2023/09/13 12:25] (current)
pzhou
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-====== HW 3 ======+====== Homework 3 ======
 (Due Wednesday, Sep 13) (Due Wednesday, Sep 13)
  
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 3. let $z = 2 e^{i \pi / 3}$. What does $z^i$ mean? is it multivalued? How about $z^{1/2}$?  3. let $z = 2 e^{i \pi / 3}$. What does $z^i$ mean? is it multivalued? How about $z^{1/2}$? 
  
-4. express $\sin(1+2 i)$ in terms of exponential. Is it true that $\sin(z) = Re( e^{i z})$ for all real $z$, for all complex $z$? +4. express $\sin(1+2 i)$ in terms of exponential. Is it true that $\sin(z) = Im( e^{i z})$ for all real $z$, for all complex $z$? (corrected, previous question was asking $\sin(z) = Re( e^{i z})$, which is false even for $z$ real)
  
 5. What is the Laurent expansion (first 3 terms) of $\frac{\cos(z)}{z}$ around $z=0$? $\frac{\cos(z)}{\sin(z)}$ around $z=0$?  5. What is the Laurent expansion (first 3 terms) of $\frac{\cos(z)}{z}$ around $z=0$? $\frac{\cos(z)}{\sin(z)}$ around $z=0$? 
  
  
math121a-f23/hw_3.1694234752.txt.gz · Last modified: 2023/09/08 21:45 by pzhou