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What is the value of x-y? [#permalink]
29 May 2007, 05:19
67% (01:39) correct
33% (05:47) wrong based on 4 sessions
I am struggling with this one. Any Help?
What is the value of x-y?
1) x=y+3 2) x^2-2xy+y^2=9
I get the answer somewhat, but statement #2 is confusing me bc I though that sqrt(9) = POSITIVE 3 only, not +3 or -3. Because once you factor out the statement and get (x-y)(x-y)=9 --> (x-y)^2=9, the answer says by squaring both sides you get two possible solutions, x-y=3 and x-y=-3, but isnt the sqrt of both sides leaving you with x-y=+3 bc its only a positive root? Any ideas on this one this whole sqroot + versus - business? Thanks