Because x < 0 - X equal to X>0
So sq of xx must be x.
Is -x the answer?
thanks
roots
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Stuart@KaplanGMAT
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We know that performing the root operation always leaves us with a non-negative result. So, we can quickly eliminate any negative answer.
Since x < 0, the answer can't be x.
Eliminate B and E.
So, we basically have:
root(x^2)
and, since the answer can't be x, it must be -x... choose A.
Here's the general rule:
if x is positive, then root(x^2) = x; and
if x is negative, then root(x^2) = -x.
This is the same rule for absolute values:
if x is positive, then |x| = x; and
if x is negative, then |x| = -x.
Since x < 0, the answer can't be x.
Eliminate B and E.
So, we basically have:
root(x^2)
and, since the answer can't be x, it must be -x... choose A.
Here's the general rule:
if x is positive, then root(x^2) = x; and
if x is negative, then root(x^2) = -x.
This is the same rule for absolute values:
if x is positive, then |x| = x; and
if x is negative, then |x| = -x.
Stuart Kovinsky | Kaplan GMAT Faculty | Toronto
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liferocks
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Hi Stuart,Stuart Kovinsky wrote:We know that performing the root operation always leaves us with a non-negative result. So, we can quickly eliminate any negative answer.
I didn't understand the quoted section. If we 'eliminate any negative answer' then we will eliminate the correct ans in first step .Can you please elaborate.
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Testluv
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Because x is negative, "-x" is positive.I didn't understand the quoted section. If we 'eliminate any negative answer' then we will eliminate the correct ans in first step .
-x = (-1)*(neg)
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