Find |−12|.
Incorrect answer: −12
Absolute value is not the same as changing every sign in an expression. First simplify what is inside the bars. Also, −|5| equals −5 because the outside negative remains.
Keeping a negative sign on absolute value
Absolute value is a distance from zero. Evaluate the expression inside first, then take that distance.
The correction
12
−12 is twelve units from zero.
- Locate the number relative to zero.
- Count or calculate the distance to zero without a direction sign.
- Evaluate expressions inside absolute-value bars before taking their absolute value.
Try the reasoning in another example
Find |3 − 7|.
- Calculate inside the bars: 3 − 7 = −4.
- The distance from −4 to zero is 4.
Answer: 4
Explain why each step preserves the quantity or relationship. If you can compute the answer but cannot explain the step, revisit the model before adding more questions.
The short check below reuses the first example as a retrieval question and adds a second question. It checks this method; it does not establish a grade level.
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