Hi All,
One of the standard Algebraic concepts that you'll see more than once on Test Day is the concept of "squared values." To test your "thoroughness" on this subject, the Test will throw the concept at you in a few different formats. Keep in mind that the rules are the always the same, but you have to pay attention to what you're looking at to get the points.
Here, we're told that X and Y are NON-0 NUMBERS. We're asked for the value of Y/X.
Fact 1: X = 6
This tells us NOTHING about Y. Since Y can be anything except 0, there are an infinite number of different possible values for Y/X.
Fact 1 is INSUFFICIENT
Fact 2: Y^2 = X^2
Here, we can TEST VALUES to prove a point....
IF.....X = 1, then we have...
Y^2 = 1
Since we have a squared value, there are 2 solutions: Y = 1 and Y = -1
IF....
X = 1
Y = 1
The answer to the question is 1/1 = 1
IF....
X = 1
Y = -1
The answer to the question is -1/1 = -1
Fact 2 is INSUFFICIENT
Combined, we know....
X = 6
Y^2 = X^2
Notice the issue in Fact 2....it's the same issue here....
We know that X = 6, so Y^2 = 36. But since we have a squared value, there are 2 solutions: Y = 6 and Y = -6.
IF....
X = 6
Y = 6
The answer to the question is 6/6 = 1
IF....
X = 6
Y = -6
The answer to the question is -6/6 = -1
Combined, INSUFFICIENT
Final Answer:
GMAT assassins aren't born, they're made,
Rich
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