Problem: The inequality is satisfied if and only if
Answer Choices:
A. or (or both inequalities hold)
B. or (or both inequalities hold)
C.
D.
E. and
Solution:
Consider two cases:
Case 1. If then if and only if , or equivalently, .
Case 2: If then if and only if , or equivalently, .
The pairs satisfying the conditions described in either Case 1 or (case 2 are exactly He pairs ( ) such that or (see adjoining diagram for geometric imerpretation).
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