Solving Absolute Value Equations

Concept

Absolute Value Equation

An absolute value equation is an equation that involves the absolute value of a variable expression. | 2x-8 |=5 Equations of the form |x|=a, where a is a real number greater than zero, can be solved by looking for the numbers x whose distance from 0 in the number line equals a. For example, the solutions of |x|=4 are all values of x that are 4 units away from 0.

Since there are two points on the number line that fulfill this requirement, there are two solutions to the equation |x|=4, namely x=4 and x=- 4. However, solving an absolute value equation, in general, might require a more elaborate and structured approach.

Number of Solutions

Simple absolute value equations of the form |x|=a, can have no, one, or two solutions, depending on the value of a. However, more complex absolute value equations may have more than two solutions.

Equation Number of Solutions Solution(s)
|x|=- 4 Zero No solution
|x|=0 One 0
|x|=4 Two - 4, 4
|x^2-4 |=2 Four - sqrt(2), sqrt(2), - sqrt(6), sqrt(6)
Exercises
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