If x<0 then |x| = -x,
then sqrt {(-x)*|x|} = sqrt {(-x)^2}
= sqrt (x^2) = |x|
and |x| = -x
Thus the answer should be A.
Or you can also apply some tips here:
the function contains only x, then the answer cannot be a specific number. Thus the answer cannot be 1 or -1. Eliminate B,C
The square root of a negative number does not exist. Thus eliminate E, sqrt (x) cannot exist as x<0.
Only A and D remain.
The result of a square root is positive, thus D is eliminated as x<0. For example: sqrt(3) = 1.7 not -1.7.
Hence pick A.
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Source: Beat The GMAT — Problem Solving |
x < 0 => |x| = -x (Think about it!)
sqrt[(-x)*(|x|)] = sqrt[(-x)*(-x)] = sqrt[x^2] = |x| = -x
The correct answer is A.
sqrt[(-x)*(|x|)] = sqrt[(-x)*(-x)] = sqrt[x^2] = |x| = -x
The correct answer is A.
Rahul Lakhani
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
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Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
