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Homework Help: Problem involving del operator in vector analysis

  1. Nov 26, 2009 #1
    1. The problem statement, all variables and given/known data
    prove grad(f/g)=((g grad f)-(f grad g))/g^2,if g not equal to 0.

    2. Relevant equations

    no idea.

    3. The attempt at a solution
    rhs will be grad f -(f grad g)/g^2.
    can't make out what 2 do after that.referred other books but no help.it's a very obscure identity.found this in m.r.spiegel's vector analysis no.57 pg-78,chap GDC.
  2. jcsd
  3. Nov 26, 2009 #2
    Use the definition of the del operator; otherwise you are just staring at upside-down triangles wondering what to do.

    [tex]\nabla (f/g) = \frac{\partial (f/g)}{\partial x}i +\frac{\partial (f/g)}{\partial y}j + \frac{\partial(f/g)}{\partial z}k[/tex]
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