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November 2nd, 2010, 09:56 AM  #1 
Member Joined: Apr 2010 Posts: 91 Thanks: 0  Complex numbers question
Which complex numbers satisfy: ? Attempt: I am not sure what else there is to do 
November 2nd, 2010, 12:07 PM  #2 
Senior Member Joined: Oct 2009 Posts: 105 Thanks: 0  Re: Complex numbers question
Actually, you know that is a real number. Thus, z must be a real number. When does whenever x is a real number? 
November 3rd, 2010, 06:15 AM  #3  
Member Joined: Apr 2010 Posts: 91 Thanks: 0  Re: Complex numbers question Quote:
 
November 3rd, 2010, 09:27 AM  #4 
Senior Member Joined: Oct 2009 Posts: 105 Thanks: 0  Re: Complex numbers question
1 =\= 1

November 3rd, 2010, 11:11 AM  #5 
Senior Member Joined: Oct 2009 Posts: 105 Thanks: 0  Re: Complex numbers question
See, the problem is that x^2 doesn't have an inverse! The sqrt is not a function (do you see why?).

November 6th, 2010, 12:09 AM  #6  
Member Joined: Apr 2010 Posts: 91 Thanks: 0  Re: Complex numbers question Quote:
 
November 6th, 2010, 02:44 AM  #7 
Senior Member Joined: Oct 2009 Posts: 105 Thanks: 0  Re: Complex numbers question
Precisely. In case you're wondering though, represents positive values only, since it doesn't have a plus or minus sign in front of it. 
November 16th, 2010, 04:27 PM  #8 
Senior Member Joined: Dec 2008 Posts: 306 Thanks: 0  Re: Complex numbers question
Six, do you know what sqrt is?

November 16th, 2010, 05:49 PM  #9 
Senior Member Joined: Oct 2009 Posts: 105 Thanks: 0  Re: Complex numbers question
Could you please elaborate instead of asking a silly question? Just tell me what's wrong with my reasoning instead, please.

November 16th, 2010, 06:55 PM  #10 
Senior Member Joined: Dec 2008 Posts: 306 Thanks: 0  Re: Complex numbers question
Sqrt is certainly a function. It is defined to be the inverse of restricted to . When solving quadratic equations you must use a plus and minus sqrt , but sqrt as a function has nothing to do with +/


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