If (X/|Y|) =-1 which of the following must be true?
A)X=-Y
B)X=Y
C)X=Y^2
D)X^2=Y^2
E)X^3=Y^3
Source-GMATPrep EP-2
OA:D
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If (x/|y|) =-1
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Hi NandishSS,
This question can be solved by TESTing VALUES (although you'll have to TEST more than one pair of values for X and Y to get to the correct answer).
We're told that X/|Y| = -1. We're asked which of the following MUST be true (which really means "which of the following is ALWAYS true no matter how many different examples we can come up with?")
Let's start with....
X = -2, Y = 2
This eliminates Answers B, C and E.
Next, notice that the absolute value around the Y... It will turn negative numbers into positive numbers.
If we try....
X = -2, Y = -2
Then this eliminates Answer A.
Final Answer: D
GMAT assassins aren't born, they're made,
Rich
This question can be solved by TESTing VALUES (although you'll have to TEST more than one pair of values for X and Y to get to the correct answer).
We're told that X/|Y| = -1. We're asked which of the following MUST be true (which really means "which of the following is ALWAYS true no matter how many different examples we can come up with?")
Let's start with....
X = -2, Y = 2
This eliminates Answers B, C and E.
Next, notice that the absolute value around the Y... It will turn negative numbers into positive numbers.
If we try....
X = -2, Y = -2
Then this eliminates Answer A.
Final Answer: D
GMAT assassins aren't born, they're made,
Rich
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You could also do this one algebraically: (X/|Y|) =-1 If we multiply both sides by |Y| we get X = -1 * |Y|. If we square both sides we'll haveNandishSS wrote:If (X/|Y|) =-1 which of the following must be true?
A)X=-Y
B)X=Y
C)X=Y^2
D)X^2=Y^2
E)X^3=Y^3
Source-GMATPrep EP-2
OA:D
X^2 = (-1)^2 * |Y|^2. Well, (-1)^2 is just 1. And |Y|^2 must equal Y^2, so X^2 = (-1)^2 * |Y|^2 becomes X^2 = Y^2. Answer is D
