Brent@GMATPrepNow wrote:I made up this question while in the shower and thought I'd post it.

Is |x| > 0?

1) 5(x^2)(y^3) < 0

2) (3y^3 - 3xy + 3x^3)/3x > 0

Hint: This one is an excellent candidate for rephrasing the target question.

Cheers,
Brent

Target question: Is |x| > 0

Notice that the absolute value of ANY number will be greater than or equal to 0. In fact, there's only one way that |x| is not greater than 0. If x=0, then |x| is not greater than 0.

So, we could rephrase the target question as: Does x equal any number other than zero?
An even better way to rephrase the target question is to ask, Does x=0?
If we know the answer to this question, then we know the answer to the question "Is |x| > 0?"

Now that we've rephrased the target question as "Does x=0?" we're ready to check the statements.

Statement 1: 5(x^2)(y^3) < 0
If 5(x^2)(y^3) < 0, then we can be certain that x does not equal 0. (If x=0, then 5(x^2)(y^3) = 0)
As such, statement 1 is SUFFICIENT


Statement 2: (3y^3 - 3xy + 3x^3)/3x > 0
If x=0, then (3y^3 - 3xy + 3x^3)/3x is undefined. Therefore, if x=0, then (3y^3 - 3xy + 3x^3)/3x could not be greater than zero.
Since (3y^3 - 3xy + 3x^3)/3x > 0, we can be certain that x does not equal 0.
As such, statement 2 is SUFFICIENT

The answer is D

Cheers,
Brent