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Source: — Data Sufficiency |
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by eagleeye » Sat Aug 04, 2012 5:02 pm
grandh01 wrote:If x ≠ 1, is y equal to x + 1?
(1) y-2/x-1=1
(2) y^2 = (x + 1)^2
Statement 1:
(y-2)/(x-1) = 1
=> y-2 = x-1
=> y = x+1
Sufficient.

Statement 2:
y^2 = (x+1)^2
=> y = either (x+1) or -(x+1).
We get two values for y. Insufficient.

A is correct. :)
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by grandh01 » Sat Aug 04, 2012 6:01 pm
Eagleeye I have one question. For the second statement y^2=(x+1)^2, when we square root both sides we have to take it to mind that (x+1) could be negative or positive right?
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by eagleeye » Sat Aug 04, 2012 6:38 pm
grandh01 wrote:Eagleeye I have one question. For the second statement y^2=(x+1)^2, when we square root both sides we have to take it to mind that (x+1) could be negative or positive right?
well, i am not sure whether you are asking this, but whenever we take the square root of a quadratic equation we have to consider both the positive and negative sign. I think that's what you're asking. For more about this, check this out:

https://www.beatthegmat.com/post476551.html

Let me know if you have any questions :)
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