### Author Topic: TUT5101 QUIZ2  (Read 1846 times)

#### Yiheng Bian

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##### TUT5101 QUIZ2
« on: January 30, 2020, 12:42:13 AM »
Question:
$$h(z)=\frac{Log(z)}{z}$$
We know when
$$z \rightarrow \infty$$
$$Log(z) \rightarrow \infty$$
So we can use L'Hopital rules and get
$$\frac{1}{z}$$
So
$$\text{limit is zero}$$

#### Victor Ivrii

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##### Re: TUT5101 QUIZ2
« Reply #1 on: January 30, 2020, 06:39:52 AM »
Wrong reasoning

#### Yiheng Bian

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##### Re: TUT5101 QUIZ2
« Reply #2 on: January 30, 2020, 09:25:16 PM »
Sorry sir, , could you point it out?

#### Victor Ivrii

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##### Re: TUT5101 QUIZ2
« Reply #3 on: January 31, 2020, 09:05:11 AM »
You cannot use LH out of the box for complex variables. You need to consider $z=re^{i\theta}$ and consider $\bigl|\dfrac{\operatorname{Log}(z)}{z}\bigr|$ ...

#### Yiheng Bian

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##### Re: TUT5101 QUIZ2
« Reply #4 on: January 31, 2020, 11:31:11 PM »
Ok, I got it. Thank you sir