- #1

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1/|

**r**-

**r**'| ≈ 1/r+(

**r**.

**r**')/r

^{3}

possibly you have to taylor expand twice to get this result, an attempt at which led me nowhere,

surely it cannot be this complicated.

any useful comment about this would be greatly appreciated

thank you

- Thread starter xBorisova
- Start date

- #1

- 4

- 0

1/|

possibly you have to taylor expand twice to get this result, an attempt at which led me nowhere,

surely it cannot be this complicated.

any useful comment about this would be greatly appreciated

thank you

- #2

TSny

Homework Helper

Gold Member

- 12,611

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As a hint, note that for any vector ##\textbf{A}##, ##|\textbf{A}| = \sqrt{\textbf{A}\cdot \textbf{A}}##.

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