Solving Absolute Value Equations: A Step-by-Step Guide

In the realm of algebra, absolute value equations present a unique challenge. Understanding how to solve them is essential for mastering algebraic concepts. This guide will walk you through the process of solving absolute value equations, providing clear explanations and illustrative examples.

What are Absolute Value Equations?

An absolute value equation involves an expression containing the absolute value of a variable or a combination of variables. The absolute value of a number is its distance from zero on the number line, always represented as a positive value.

For example, the absolute value of 5, denoted as |5|, is 5. Similarly, the absolute value of -5, denoted as |-5|, is also 5.

Solving Absolute Value Equations: A Step-by-Step Approach

Solving absolute value equations requires a slightly different approach compared to solving regular linear equations. Here’s a step-by-step process:

1. Isolate the Absolute Value Expression: Begin by isolating the absolute value expression on one side of the equation. This involves performing algebraic operations such as addition, subtraction, multiplication, or division.
2. Set Up Two Equations: Since the absolute value of a number is its distance from zero, there are two possible cases:
• Case 1: The expression inside the absolute value is positive.
• Case 2: The expression inside the absolute value is negative.
3. Solve Each Equation: Solve each of the two equations you set up in step 2. This involves applying standard algebraic techniques to find the solutions for each case.
4. Check for Extraneous Solutions: It’s crucial to check your solutions by substituting them back into the original equation. Sometimes, a solution might satisfy the equations you derived but not the original absolute value equation. These solutions are called extraneous solutions and must be discarded.

Illustrative Examples

Let’s demonstrate the process with a few examples:

Example 1:

Solve the equation: |2x – 3| = 7

1. Isolate the Absolute Value: The absolute value expression is already isolated.
2. Set Up Two Equations:
• Case 1: 2x – 3 = 7
• Case 2: 2x – 3 = -7
3. Solve Each Equation:
• Case 1: 2x = 10, x = 5
• Case 2: 2x = -4, x = -2
4. Check for Extraneous Solutions:
• For x = 5: |2(5) – 3| = |7| = 7 (Valid)
• For x = -2: |2(-2) – 3| = |-7| = 7 (Valid)

Therefore, the solutions to the equation |2x – 3| = 7 are x = 5 and x = -2.

Example 2:

Solve the equation: |x + 1| – 2 = 5

1. Isolate the Absolute Value: Add 2 to both sides: |x + 1| = 7
2. Set Up Two Equations:
• Case 1: x + 1 = 7
• Case 2: x + 1 = -7
3. Solve Each Equation:
• Case 1: x = 6
• Case 2: x = -8
4. Check for Extraneous Solutions:
• For x = 6: |6 + 1| – 2 = |7| – 2 = 5 (Valid)
• For x = -8: |-8 + 1| – 2 = |-7| – 2 = 5 (Valid)

Therefore, the solutions to the equation |x + 1| – 2 = 5 are x = 6 and x = -8.

Conclusion

Solving absolute value equations involves a methodical approach that considers both positive and negative cases. By following the step-by-step guide and carefully checking for extraneous solutions, you can confidently solve these equations and enhance your understanding of algebraic concepts.