they refer to a product rule 5 for the second last equality above. This text is taken from David Griffiths, introduction to electrodynamics. If anyone is familiar with the book. At what page is product rule 5 that is used here introduced? I cant find that page. Or does anyone have another book or a internet site where this product rule 5 is derived? Or does anyone want to derive the second last equality above here on this page?

 

On a further note I understand that

So I understand how they obtain the left side of:

 

Edited December 5, 20196 yr by Tor Fredrik

2 hours ago, Tor Fredrik said:

they refer to a product rule 5 for the second last equality above. This text is taken from David Griffiths, introduction to electrodynamics. If anyone is familiar with the book. At what page is product rule 5 that is used here introduced? I cant find that page. Or does anyone have another book or a internet site where this product rule 5 is derived? Or does anyone want to derive the second last equality above here on this page?

 

All the 8 product rules he uses are listed inside the front cover.

I can look later on when I get home and look at my hardcopy

6 hours ago, Mordred said:

I can look later on when I get home and look at my hardcopy

I found it but thanks anyway.