Two students discuss an unknown number \(z\).
Ethan says, “The absolute value of \(z\) is at most \(6\).”
Maya says, “The distance from \(z\) to \(4\) on the number line is at most \(3\).”
Does every number that satisfies Maya's statement also satisfy Ethan's statement? Determine both solution sets and justify your answer.
Hints
- Rewrite each absolute value statement as an interval.
- Interpret \(|z - 4|\) as distance from \(4\).
- Compare the endpoints of the two intervals.
- Look for a counterexample in Maya's interval but outside Ethan's.
Solution
1. Ethan's statement is \(|z| \le 6\), which is equivalent to \(-6 \le z \le 6\).
2. Maya's statement is \(|z - 4| \le 3\), which is equivalent to \(1 \le z \le 7\).
3. Maya's interval extends to \(7\), while Ethan's interval ends at \(6\).
4. The number \(7\) is a counterexample: it is \(3\) units from \(4\), but \(|7| = 7 > 6\).
5. Therefore, not every number satisfying Maya's statement satisfies Ethan's statement.
Answer
No. Maya''s solution set is \([1, 7]\), while Ethan''s is \([-6, 6]\). For example, \(z = 7\) satisfies Maya''s condition but not Ethan''s.