Source: Official Guide Revised GRE 2nd Ed. Part 9; Section 5; #24

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# If x y 0 , which of the following

If x y 0 , which of the following inequalities must be true? y + 1 x, y - 1 x,xy x, xy y, xy x

### 2 Explanations

1

If x = -1/2 and y = -1/4; The option B (y-1 < x) works perfectly. Why are't these values considered.

May 23, 2015 • Comment

Jonathan , Magoosh Tutor

Vishnu, remember that the question is asking which MUST be true. You are correct that (B) is true for those particular values. But, for other values of x and y, (B) is not true. For example, if x = -5, and y = -1, then (B) is NOT true. The correct answer is true for ALL valid values of x and y. (E) is the only answer choice.

P P

But when we are dealing with QC questions we always just need to find something that could work sometimes. Why is it different In this case.

For this one, we are trying to find out "which of the following inequalities MUST be true." This means that we need a choice that works for all possible values, not just one. If the question asked us for values that COULD be true, then we would only need one correct example.

1

Chris Lele

Dec 8, 2012 • Comment