The book now says:

The first moment about an axis *a* is

*µ _{a}* = ( x - a ) ƒ(x) dx
, (10.1)

where *µ* is a moment with the subscript a denoting the
axis. When *a *= 0, *µ'* is the mean. The second moment about
the mean is

*µ _{2}*
= ( x
- a )

This is wrong.

The correct equation is:

*µ _{2}*
= ( x -

On page 177, Equation 10.4 did not come out right. It should be: