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Complex numbers

  1. May 14, 2012 #1
    1. The problem statement, all variables and given/known data

    solve the following and determine if it is complex, real and/or imaginary

    x2 = 1



    3. The attempt at a solution

    The answer is x = +-1 which I agree with but the book says that that is complex and real. How complex? Complex numbers have the form a + bi, there's no bi in that answer.
     
  2. jcsd
  3. May 14, 2012 #2
    ##\mathbb{R} \subseteq \mathbb{C}##

    A complex number ##c## can represented as ##c = a + bi## where ##a,b \in \mathbb{R}##

    In this case, b=0. A purely imaginary number is when a=0.
     
  4. May 14, 2012 #3
    They're trying to get you to see that real numbers are complex numbers. But it's a little misleading, since clearly if someone asks if 1 is "real or complex," the answer is real ... even though technically, the right answer is "both." I think this is a bit of a trick question.
     
  5. May 14, 2012 #4
    thanks, I did feel tricked, but I get the point now.
     
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