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Sqrt of complex number

• To: mathgroup at smc.vnet.net
• Subject: [mg126634] Sqrt of complex number
• From: Jacare Omoplata <walkeystalkey at gmail.com>
• Date: Sun, 27 May 2012 04:42:36 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

Hi,

When I try to find the square root of of a complex number, I get only one answer.

In[1]:= Sqrt[3-4 I]
Out[1]= 2-I

But -2+I is an answer as well.

In[2]:= (-2+I)^2
Out[2]= 3-4 I

Why does Mathematica give the first answer and not the second? Does it choose the answer with the positive real number? Is there any way I can get both answers? Or do I just have to remember that the negative of the given answer is also an answer?

Thanks.

• Follow-Ups:
  • Re: Sqrt of complex number
    • From: Murray Eisenberg <murray@math.umass.edu>
  • Re: Sqrt of complex number
    • From: "Dave Snead" <dsnead6@charter.net>
  • Re: Sqrt of complex number
    • From: Bob Hanlon <hanlonr357@gmail.com>