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Homework Help: 5 Vector Field Proofs - apparently easy

  1. Apr 27, 2012 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations
    I know the dot product and cross product, but even for the first one I don't see how either helps.

    3. The attempt at a solution
    1. the gradient of the 2 scalars multiplied together (not crossed or dotted just multiplied)
    I know that the derivative of a scalar is a vector, but that wont help here

    Can someone put me out of my misery?
  2. jcsd
  3. Apr 27, 2012 #2


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    The ith component of ##\nabla(\phi\psi)## is given by ##\frac{\partial}{\partial x_i} (\phi\psi)##. That derivative is the regular old derivative you know and love, so what do you get when you apply the product rule?
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