1. Definition
|X|≤c (c≥0) ⇔ −c≤X≤c; |X|≥c ⇔ X≤−c or X≥c; |X| is the distance from zero.
3. Properties & Laws
- |X|≤c gives an interval;
- |X|≥c gives two parts;
- c<0: none/all;
- |X|=c gives ±c.
4. Steps
- Enter a (≠0), b, c and a sign;
- Click "Solve";
- Or click "Load Example".
5. Worked Examples
Example: |2x+1|≤5 → −3≤x≤2.
6. Common Pitfalls
Ensure c≥0;
Dividing by negative a flips the sign (auto);
≥ has two parts.