Absolute Value Equation Calculator

Absolute Value Equation Calculator

Solve absolute value equations of the form a|x + b| = c and find all solutions.

Real-number coefficients only (decimals or scientific notation); complex numbers are not supported here.

2026-05-12T10:30:54.901Z
1|x + 0| = 5
Solutions
x₁ = 5
x₂ = -5

What is an Absolute Value Equation?

An absolute value equation is an equation that contains an absolute value expression. The absolute value of a number is its distance from zero on the number line, which is always non-negative. An equation like |x| = 5 means "x is 5 units away from zero," which gives two solutions: x = 5 or x = -5.

More generally, equations of the form a|x + b| = c can be solved by recognizing that the expression inside the absolute value can be either positive or negative. This leads to two separate linear equations that must be solved independently.

How to Solve Absolute Value Equations

Step-by-Step Method

  1. 1.Isolate the absolute value expression on one side of the equation.
  2. 2.Check if the constant on the right side is negative. If yes, there is no solution.
  3. 3.Set up two separate equations: one where the expression inside equals the positive constant, and one where it equals the negative constant.
  4. 4.Solve each equation separately to find all possible solutions.
  5. 5.Verify your solutions by substituting them back into the original equation.

The solver automatically divides by coefficient a so the absolute value term becomes isolated even when a ≠ 1. When you take these same steps to inequalities, dividing by a negative a flips the inequality direction, though equalities (like the ones solved here) stay unchanged.

The General Formula

For a|x + b| = c where c ≥ 0:
First divide by a: |x + b| = c/a
Then solve two cases:
Case 1: x + b = c/a   ⟹   x = -b + c/a
Case 2: x + b = -c/a   ⟹   x = -b - c/a

Example: Solving 2|x - 3| = 10

Solve: 2|x - 3| = 10

Step 1:
Divide both sides by 2 to isolate the absolute value: |x - 3| = 5.
Step 2:
The right side is 5 (non-negative), so solutions can exist.
Step 3:
Set up two equations:
• 2(x - 3) = 10 → x - 3 = 5 → x = 8
• 2(x - 3) = -10 → x - 3 = -5 → x = -2
Step 4:
Verify:
• 2|8 - 3| = 2|5| = 10 ✓
• 2|-2 - 3| = 2|-5| = 10 ✓
Result:
x = 8 or x = -2

Frequently Asked Questions

Can an absolute value equation have no solution?

Yes. If the equation requires the absolute value to equal a negative number (e.g., |x| = -3), there is no solution because absolute values are always non-negative.

Can there be only one solution?

Yes. This happens when the right side equals zero (e.g., |x| = 0 gives only x = 0) or when both cases yield the same solution.

Do I always get two solutions?

Not always. You may get two distinct solutions, one solution, or no solution depending on the equation.

What if there are absolute values on both sides?

You'll need to consider multiple cases based on the signs of the expressions inside each absolute value. This can lead to up to four separate equations to check.

How do I verify my solutions?

Substitute each solution back into the original equation. If both sides are equal, the solution is correct. Always check your work!

What's the difference between |x| = 5 and the inequality |x| < 5?

The equation |x| = 5 has exactly two solutions: x = 5 or x = -5. The inequality |x| < 5 has infinite solutions: all x between -5 and 5.

What are extraneous solutions?

Extraneous solutions are values that arise when solving an equation but don't satisfy the original equation. Always check your solutions by substituting back into the original equation.

Can absolute value equations appear in real-world contexts?

Yes! They model situations involving distance, tolerance, error bounds, and any scenario where you need to find values at a fixed distance from a target. Common in engineering and physics.

Can I use complex coefficients here?

No, this calculator only accepts real-number coefficients (decimals or scientific notation). Complex tasks need a symbolic or complex-number solver.

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