stonecold wrote:

Is x=y?

[A] x² = xy

[B] x² = y²

Vyshak's solution is great, so I won't re-answer the question.

I just want to point out that the intended TRAP here is that some people will

incorrectly take the equation x² = xy and divide both sides by x to get x = y

People who do that will incorrectly conclude that the answer is A.

The problem with taking the equation x² = xy and dividing both sides by x is that you may be dividing both sides by zero, which is a big no-no.

Likewise, if we take this valid equation, (2)(0) = (1)(0) and divide both sides by 0, we can't then conclude that 2 = 1

Cheers,

Brent

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Brent Hanneson – Founder of gmatprepnow.com