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Homework Help: What does Re mean?

  1. Nov 9, 2011 #1
    1. The problem statement, all variables and given/known data
    number 2a)

    2. Relevant equations

    3. The attempt at a solution

    I just need help knowing what Re means. I've never seen it before and the prof didn't mention it.
  2. jcsd
  3. Nov 9, 2011 #2
    "real part of", it is defined in question 2a:

    where Re(a + bi) = a for a; b 2 R
  4. Nov 9, 2011 #3
    Thanks. But now i'm confused at the problem.I'm not sure how to confirm the real parts.
    Last edited: Nov 9, 2011
  5. Nov 9, 2011 #4


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    Science Advisor

    <v,w> is going to be some complex number. take its real part.

    for example:

    <(2+3i,4-5i),(3,1-i)> = (2+3i)(3) + (4-5i)(1+i) = 6+9i + (4-(-5) + (4 - 5)i)

    = 6+9i + 9-i = 15+8i, and the real part of this is 15.
  6. Nov 9, 2011 #5

    Ray Vickson

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    Homework Helper

    You can also get the real part of a complex quantity z: [tex] \mbox{Re}(z) = \frac{1}{2}(z + \bar{z}), [/tex] where [itex] \bar{z} [/itex] is the complex conjugate of z.

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