# 5 Vector Field Proofs - apparently easy

1. Apr 27, 2012

### thomas49th

1. The problem statement, all variables and given/known data
http://gyazo.com/94783c14f2d2d05e62e479ab33c73830

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?
Thomas

2. Apr 27, 2012

### vela

Staff Emeritus
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?