The equation

 

¦a + b ¦= c, c > 0,

 

is equivalent to two equations:

 

a + b = c or a + b =- c

 

A student asked what happens if c = 0. We get one equation, of course. This needs explanation right away, especially if it is in response to a question.

 

If c < 0, we get no solution.

 

Another way of dealing with absolute values is to say that the absolute value signs can be replaced by parenthesis and by parenthesis with a negative sign.

 

SEE THE BOOK FOR MORE DETAILS.