Bunuel
If x is a positive number, is x less than 1?
(1) \(x > \sqrt{x}\)
(2) \(−\sqrt{x} > −x\)
Key properties:
Property #1: If \(0 < x < 1\), then \(x < \sqrt{x}\). For example, \(\frac{1}{4} < \sqrt{\frac{1}{4}}\)
Property #2: If \(x > 1\), then \(x > \sqrt{x}\). For example, \(9 > \sqrt{9}\)Target question: Is x less than 1? Statement 1: \(x > \sqrt{x}\) This statement is identical to
Property #2, which means x > 1
So, the answer to the target question is
NO, x is not less than 1Since we can answer the
target question with certainty, statement 1 is SUFFICIENT
Statement 2: \(−\sqrt{x} > −x\)Multiply both sides of the inequality by \(-1\) to get: \(\sqrt{x} < x\)
[Whenever we multiply both sides of an inequality by a negative value, we must REVERSE the direction of the inequality symbol]Since the resulting inequality is identical to the statement 1 inequality, statement 2 must also be SUFFICIENT
Answer: DCheers,
Brent