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Homework Help: Simple Maths

  1. Jul 14, 2005 #1
    ((-6)^ 1/2 ) ( (-7)^1/2) = (42)^1/2

    ((-6)^ 1/2 ) ( (-7)^1/2) = (6^ 1/2 ) ( 7^1/2) ( i ^2)
    = -(42)^1/2

    Can anyone tell me where I did wrong?
     
  2. jcsd
  3. Jul 14, 2005 #2

    lurflurf

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    Homework Helper

    ((-6)^ 1/2 ) ( (-7)^1/2) = (42)^1/2
    this step
    [tex]x^zy^z=(xy)^z[/tex]
    is not true in general only when x,y>0
     
  4. Jul 14, 2005 #3
    ((-6)(-7))^(1/2)=(42)^(1/2)
    (42)^(1/2)=(42)^(1/2)
    should have left the right hand side alone
     
  5. Jul 14, 2005 #4
    Thanks a lot..
     
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