Appendix A Absolute-Value Equations and Inequalities
Introduction We have seen in Section 1.1 that the absolute value of a real number x is a nonnegative quantity defined as
A review of Section 1.1 is highly recommended.
In this appendix we review two things: solving equations and inequalities that involve an absolute value.
Absolute-Value Equations From (1) we see immediately that |6| = 6 since 6 > 0 and | –6| = –(–6) = 6 because –6 < 0. This simple example suggests that the solution of the equation |x| = 6 has two solutions, namely, ...