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Absolute value inequalities calculator

Choose the comparison in |ax + b| compared with c. Brackets include endpoints and parentheses exclude them. inf means infinity.

Calculator

Solution in interval notation
(-1, 5)

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How this calculator works

A less-than comparison confines the inside expression between -c and c when c is positive. A greater-than comparison selects the two outside rays. This calculator also handles zero and negative c and constant expressions. Squaring is valid here only after treating negative c separately.

Formula

For c >= 0: |ax + b| compared with c is equivalent to (ax + b)^2 compared with c^2, using the same comparison.

Worked example

For |x - 2| < 3, subtracting the distance bound gives -3 < x - 2 < 3. Add 2 throughout to obtain -1 < x < 5, written (-1, 5).

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Frequently asked questions

Do I reverse the comparison for a negative a?

Yes when dividing an inequality by a negative value. The solver orders the endpoints after solving, so negative coefficients are supported.

What does U mean?

U joins two solution intervals. For an outside region, either interval satisfies the inequality.

Is |x| < 0 possible?

No. Its solution is the empty set, whereas |x| >= 0 holds for every real number.

Sources

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