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Complex expressions

  • #1
Hello I'm studying complex numbers for class and the question is stated as:
Let z=1+2i
Find:
a) 1/z^2
b) 1/z^3

I was thinking just to multiply by the conjugate (1-2i)^2 for (a) and similarly for (b).
Would that be correct in solving it?
 

Answers and Replies

  • #2
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10,340
You can do that, right.
Alternatively, calculate 1/z first, and then calculate powers of that.

As this looks like homework, I moved your thread.
 
  • #3
Oh thank you!
I apologize if I put it in the wrong thread!
 
  • #4
237
5
Oh thank you!
I apologize if I put it in the wrong thread!
Firstly, let's establish what you are actually asking.

For example, the way you wrote it, 1/z^2 = [itex]\frac{1}{z^2}[/itex], NOT [itex](\frac{1}{z})^2[/itex]

EDIT: Please ignore. Complete brain-fart by me there! :redface:
 
Last edited:
  • #5
34,303
10,340
For example, the way you wrote it, 1/z^2 = [itex]\frac{1}{z^2}[/itex], NOT [itex](\frac{1}{z})^2[/itex]
Where is the difference?
 
  • #6
237
5
Where is the difference?
Thanks. I simply cannot believe what I wrote in my previous post.

I blame lack of sleep...:zzz:
 
  • #7
HallsofIvy
Science Advisor
Homework Helper
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Surely there must be some way to completly delete a post so that those of us who post a really stupid idea can pretend it never happened!?
 

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