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wat's da catch

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wat's da catch

by sanju09 » Fri May 15, 2009 6:18 am
Is a b positive?
1. (a + b)^2 < (a - b)^2.
2. a = b.


IMO A
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by mike22629 » Fri May 15, 2009 8:29 am
IMO A.

(a+b)^2 = a^2+2ab+b^2
(a-b)^2 = a^2 -2ab+b^2

Statement One Tells you that right side is bigger
Hence 2ab<-2ab
So ab must be negative
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by sanju09 » Sat May 16, 2009 1:39 am
mike22629 wrote:IMO A.

(a+b)^2 = a^2+2ab+b^2
(a-b)^2 = a^2 -2ab+b^2

Statement One Tells you that right side is bigger
Hence 2ab<-2ab
So ab must be negative
Well done mike22629, but can you please explain the incompetency of statement (2) as well?
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Re: wat's da catch

by iamcste » Sat May 16, 2009 6:57 am
sanju09 wrote:Is a b positive?
1. (a + b)^2 < (a - b)^2.
2. a = b.


IMO A

A since a=b=0 , ab=0 Neither positive nor negative

, stmt 1 suficient as explained in the earlier post
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