The solutions to inequalities can be expressed in several ways. You can use inequality notation, interval notation, or a shaded number line. Each of these ways of describing a solution has its place in different application. None is better than another. They're just different and used for different purposes.
The number line is very helpful when solving multiple inequalities. It's an essential part of solving absolute value inequalities. Two key words in the solutions of these problems are
and and
or. In mathematics, these two words have very specific meanings. The word
and means that both requirements must be met. The word
or means that one requirement
or the other
or both must be met.