Algebra 1 Intermediate

Absolute Value Equations

Solve equations of the form |ax + b| = c by splitting into two cases — with step-by-step work and number line visualization.

Live Calculator · Step-by-Step · Algebra 1
Input
|2x − 3| = 7
Enter values for |ax + b| = c
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a
x +
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Examples
Enter values for |ax + b| = |cx + d|
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x +
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c
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Solution
Enter values and press Solve to see the solution.
Step-by-Step Solution
Number Line
How Absolute Value Equations Work
|expression| = c

The absolute value of a quantity equals its distance from zero on the number line. When you set |expression| equal to a constant c:

If c > 0: Two equations — expression = c  OR  expression = −c. Usually gives two solutions.

If c = 0: One equation — expression = 0. Exactly one solution (the expression must be zero).

If c < 0: No solution — absolute value is always ≥ 0, so it can never equal a negative number.

Always isolate the absolute value expression before splitting into cases.
Always Check Your Answers!

After solving, substitute each answer back into the original equation to verify it works. This is especially important for:

• Equations where the absolute value is not fully isolated

• More complex forms like |f(x)| = g(x) (where g(x) could be negative)

• Rational or radical equations combined with absolute value

If substituting gives a false statement, that answer is an extraneous solution and must be discarded.

Example: |2x − 3| = 7 → x = 5 gives |7| = 7 ✓   x = −2 gives |−7| = 7 ✓

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