### Section 9.8

## Equations

Unless you are following a style guide that
specifies otherwise, observe the following conventions.

Integrate equations into the body of your
document by including in the text one or more explicit references
to each one and, if appropriate, a short explanation of each
term.

Include only the main equations in the body of the document.
Detailed derivations and calculations, if appropriate, should be put in appendixes.

Set off equations from the text by displaying them, centered on the longest line, and with equation numbers as shown.

```
An ion in crossed electric and magnetic fields drifts at
right angles to both fields with a velocity of
```

(Eq. 7)

```
where V
```_{d} is the drift velocity, E_{s} is the
magnitude of the static field, and B is the magnetic field
strength. If V_{d} were to approach unity, the behavior
of the electric . . .

#### Guidelines for Displaying Equations

- Align runover lines on the equals signs (=):

- Break an equation longer than one line according to the
following order of preference:

- Immediately before the equals sign. Align the equals
sign in the second line with the first operator in the
first line.

- Immediately before an addition or subtraction sign
(
*+* or *-*) that is not enclosed in
parentheses, brackets, or braces. Align the addition
or subtraction sign starting the second line with the
equals sign in the first line.

- Immediately before a multiplication sign
(
*×*). Align the multiplication sign
starting the second line with the equals sign in the
first line.

- Between two sets of enclosures (parentheses, brackets,
or braces). Begin the second line with an explicit
multiplication sign aligned with the equals sign
followed by the second enclosed set.

## Equations ##

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