Absolute value is an operation in mathematics, written as bars on either side of the expression. For example, the absolute value of −1 is written as |−1|.
Absolute value can be thought of in three ways. First, the absolute value of any number is defined as the positive of that number. For example, |8| = 8 and |−8| = 8. Second, one absolute value equation can yield two solutions. For example, if we solve the equation |x | = 2, not only does x = 2 but also x = −2 because |2| = 2 and |−2| = 2.
Third, absolute value is defined as the distance, without regard to direction, that any number is from 0 on the real number line. Consider a formula for the distance on the real number line as |k − 0|, in which k is any real number. Then, for example, the distance that 11 is from 0 would be 11 (because |11 − 0| = 11). Likewise, the absolute value of 11 is equal to 11. The distance for −11 will also equal 11 (because |−11 − 0| = |−11| = 11), and the absolute value of −11 is 11.
Thus, the absolute value of any real number is equal to the absolute value of its distance from 0 on the number line. Furthermore, if the absolute value is not used in the above formula |k − 0|, the result for any negative number will be a negative distance. Absolute value helps improve formulas in order to obtain realistic solutions.
see also Number Line; Numbers, Real.