vinni.k wrote:GMATGuruNY wrote:
D. -3/5<x<0
E. -1<x<0
Strategy:
Test a value that is included in one range (-1<x<0) but NOT in the other range (-3/5<x<0).
x = -3/4 is included E's range but not in D's range.
Mitch, this strategy is good, but if we don't take values from D's range -3/5<x<0, then doesn't it mean that we are not using inequality of D ? I mean to say i take one value that is included in one range (-1<x<0) but NOT in the other range (-3/5<x<0), now it gives me an impression that i am not using choice D for checking. Something out of the range will definitely not satisfy the inequality.
The correct answer choice must include ALL POSSIBLE VALUES OF X.
In testing x=-3/5 -- a value
within E's range but
outside D's range -- we are in fact checking whether D includes ALL possible values of x.
Since x=-3/5 satisfies the inequality in the question stem, D's range does NOT include all possible values of x.
Eliminate D.
Another case:
If |2x - 3| < 11, which of the following expresses all possible values of x?
A: -7 < x < 4
B: -4 < x < 7
Here, we should test a value between the two upper boundaries (4 and 7) or between the two lower boundaries (-7 and -4).
Test x=5, which is included in B's range but not in A's range:
|2*5 - 3| < 11
7 < 11.
This works.
The correct answer choice must include x=5 within its range.
Eliminate A.
The correct answer is B.
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