### Author Topic: Sample Final, Q4, (c)  (Read 1348 times)

#### Ende Jin

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##### Sample Final, Q4, (c)
« on: December 06, 2018, 12:15:20 PM »
I just want to ask, if that is the answer. Because the author just took off the absolute value without reason ($z \in \mathbb{C}$ right?) and when dealing with $arg(f'(z))$ I don't understand why the simplification is necessary. Why not just write $arg(f'(z)) = arg(\frac{-24}{(1+5z)^2})$ Why it has to move $\pi$ out?