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for DS questions - square root

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Source: — Data Sufficiency |
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by DanaJ » Wed Mar 18, 2009 2:40 am
Yes, you can safely say that 1 is sufficient, since sqrt(x) is always positive.
If x = 1, then x - 2 = -1, which is negative, and you'd have a case of positivie = negative.
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Re: for DS questions - square root

by marcusking » Wed Mar 18, 2009 4:32 am
crossingfingers wrote:Lets say the question says...

whats the value of x?

1. sq root(x) = x-2

solving we get x=4 and x=1

However x=1 doesnt satisfy the above equation...and the ans is x=4...so can we say Statement 1 is sufficient?

Thanks
Keep in mind also that if x was 4 you could also end up -2 = 4-2 or -2 = 2.

Almost 100% of the time with DS questions and you see anything about sqrt or x^2 you're going to have to deal with +/- signs that usually make one or more statements ambiguous and thus insufficient. You've done a good job picking up on this (I still get tripped up when I rush through questions to fast)
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