1. Apr 27, 2012

### mcheung4

1. find ∂r/∂x$_{j}$, where r=|$\underline{x}$|

2. is this the same as differentiating a modulus of a vector?

2. Apr 27, 2012

### phyzguy

Try writing r out in components, i.e. r = f(x1,x2,x3,...) and I think it will be obvious what you need to do.

3. Apr 27, 2012

### mcheung4

thats what i dunno... what is the component for a mod x?