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GMAT Prep 1 DS Q1

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Source: — Data Sufficiency |
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by jangojess » Wed Oct 24, 2007 1:20 pm
in Qs like these a better way wud be to take each statement and plug in values until u get an INSUFF for a stmt...not necessary that u shld get an INSUFF ans but always keep ur mind to get values for x so that you can brk the cond...... :)

stmt1 - x having a value anything other than 3.
x = 5 ==> rt(2^2) = -2 ??? the ans is NO
x = 1 ==> rt(-2^2) = 2 ??? the ans is NO
x = -2.5 ==> rt(-5.5^2) = 5.5 ??? the ans is NO...In any case the ans wud be NO....So suff

stmt2 - -x|x| > 0 this means that x shld be < 0...Just as done above any -ve value wud give a DEFINITE NO....So suff........IMO ans is D.
Trying hard!!!
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by me4mba » Fri Oct 26, 2007 4:20 am
I don't really get this problem. Maybe someone can explain to me.

What I would do is to square both sides to get rid of the square root. That gives me:

(x-3)^2 = (3-x)^2

At this point, any value for x would work because of the "sqaure". My question is... is squaring both sides a valid strategy?

Another thing... can a negative number be a result of a square root? For example, if you have sqrt((-5)^2), would you square the -5 first before taking the square root (so the final answer would be 5), or would you just cancel out the square and square root, so the answer would be -5??? Thanks!
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by raulverde » Fri Oct 26, 2007 9:07 am
Whenever you are asked something of the form : ((x-a)2)^1/2
Its same as : |x-a|

Stmt 1 : if x = 2 , then Both sides are equal.
if x = 10, then both sides aren't equal

Stmt 2 : says that x is -ve. try plugging in values and you will see that both sides are always equal.

Hence B
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by raulverde » Fri Oct 26, 2007 9:08 am
I am sorry . I meant : ((x-a)^2)^1/2
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by ri2007 » Thu Nov 08, 2007 10:16 am
ack,

can you pls confirm the ans to this question? The way I look at it the only way

x-3 = 3-x is if x = 3.

Stat1) x not not equal to 3. So we can say safely answer that x-3 is not = 3-x so suff

stat2) x is a negative no. so again can say safely answer that x-3 is not = 3-x so suff

So my ans would be D

However this is diff from what the other people on the forum have answered.

Can any one else confirm or explain?

thanks
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