Solving Homework Questions: Modulus, Arg, Roots

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Homework Help Overview

The discussion revolves around complex numbers, specifically focusing on modulus, argument, and roots. Participants are addressing two questions related to these concepts, with particular emphasis on calculating arguments and roots of complex numbers.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss their attempts to find the smallest and largest arguments of a complex number and express confusion about the correct method to achieve this. There is also mention of potential missing steps in solving the second question.

Discussion Status

Some participants have provided partial answers and expressed uncertainty about their correctness. There is a suggestion to separate the questions into distinct threads for clarity. Guidance has been offered regarding the nature of roots of unity and the importance of expressing complex numbers in polar form.

Contextual Notes

Participants are encouraged to type out problems and solutions instead of relying solely on images, as this may facilitate better understanding and responses.

King_Silver
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Homework Statement


First question = attached below
Second Question = attached below

Homework Equations


modulus, argument, roots.

The Attempt at a Solution


For the 1st question I've gotten the modulus, the principal argument and the abs. of z^1/4 which was something like 1.5335 I believe. The only thing I am not understanding with regards to this question is the final part, where it is asking for the smallest argument, 2nd smallest, 2nd largest and largest in that ascending order.
I've tried several things but none of them have worked to give me a proper answer. I'm probably missing something really stupid like "Just divide it by x to find smallest, add x to find largest, take away x to find second smallest" or some standard format like that.

2nd question I got these as my answers
1: e^(3x)
2: -3y

3: -(i*arg(-2+4i))/3 + ln(abs(-2+4i))/3

yet they don't seem to be the correct answers, I think I must be leaving out a step in the 2nd one.
 

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King_Silver said:

Homework Statement


First question = attached below
Second Question = attached below

Homework Equations


modulus, argument, roots.

The Attempt at a Solution


For the 1st question I've gotten the modulus, the principal argument and the abs. of z^1/4 which was something like 1.5335 I believe. The only thing I am not understanding with regards to this question is the final part, where it is asking for the smallest argument, 2nd smallest, 2nd largest and largest in that ascending order.
I've tried several things but none of them have worked to give me a proper answer. I'm probably missing something really stupid like "Just divide it by x to find smallest, add x to find largest, take away x to find second smallest" or some standard format like that.

2nd question I got these as my answers
1: e^(3x)
2: -3y

3: -(i*arg(-2+4i))/3 + ln(abs(-2+4i))/3

yet they don't seem to be the correct answers, I think I must be leaving out a step in the 2nd one.
I suggest that these should be posted two threads, one thread for each problem. They are not all that similar, and each is multi-part.

It would be helpful to post the images as full-size like this:

math-2-png.95272.png
 
King_Silver said:

Homework Statement


First question = attached below
Second Question = attached below

Homework Equations


modulus, argument, roots.

The Attempt at a Solution


For the 1st question I've gotten the modulus, the principal argument and the abs. of z^1/4 which was something like 1.5335 I believe. The only thing I am not understanding with regards to this question is the final part, where it is asking for the smallest argument, 2nd smallest, 2nd largest and largest in that ascending order.
I've tried several things but none of them have worked to give me a proper answer. I'm probably missing something really stupid like "Just divide it by x to find smallest, add x to find largest, take away x to find second smallest" or some standard format like that.
When you are asked to calculate something like z1/n, you should be aware that there are n separate and distinct complex numbers, call them w1, w2, w3, ..., wn, which result. These complex numbers are related to what are known as the roots of unity, which is described here:

https://en.wikipedia.org/wiki/Root_of_unity

If you express the original complex number z in its polar form, such that z = r e i θ, then the various values of z1/n can be easily computed.
 
King_Silver said:

Homework Statement


First question = attached below
Second Question = attached below

Homework Equations


modulus, argument, roots.

The Attempt at a Solution


For the 1st question I've gotten the modulus, the principal argument and the abs. of z^1/4 which was something like 1.5335 I believe. The only thing I am not understanding with regards to this question is the final part, where it is asking for the smallest argument, 2nd smallest, 2nd largest and largest in that ascending order.
I've tried several things but none of them have worked to give me a proper answer. I'm probably missing something really stupid like "Just divide it by x to find smallest, add x to find largest, take away x to find second smallest" or some standard format like that.

2nd question I got these as my answers
1: e^(3x)
2: -3y

3: -(i*arg(-2+4i))/3 + ln(abs(-2+4i))/3

yet they don't seem to be the correct answers, I think I must be leaving out a step in the 2nd one.

You should avoid posting images only. Type out the problem if it is not long and/or complicated. Type out you solution also, to the extent possible. As Vela states in his post "Guidelines for students and helpers": "Ask yourself "If I can't be bothered to spend my time typing it, why should they be bothered to spend their time reading it, much less responding to it?" Use images for supporting figures."
 

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