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# If x + y = a and x тАУ y = b, then 2xy

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Manager
Joined: 07 Jul 2003
Posts: 56
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If x + y = a and x тАУ y = b, then 2xy [#permalink]  18 Feb 2004, 11:00
If x + y = a and x тАУ y = b, then 2xy =
Senior Manager
Joined: 05 May 2003
Posts: 427
Location: Aus
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Kudos [?]: 5 [0], given: 0

2xy = a power 2 - (x power 2 + y power 2 )
or
2xy = (x power 2 + y power 2) - b power 2
Senior Manager
Joined: 23 Aug 2003
Posts: 462
Location: In the middle of nowhere
Followers: 1

Kudos [?]: 12 [0], given: 0

x + y = a
x тАУ y = b

2x=a+b x=a+b/2
2y = a-b y=a-b/2

2xy =(a+b/2) * (a-b/2)
2xy = 2/4((a+b)*(a-b))

2xy = 1/2(a^2-b^2)

Vivek.
_________________

"Start By Doing What Is Necessary ,Then What Is Possible & Suddenly You Will Realise That You Are Doing The Impossible"

Senior Manager
Joined: 30 Aug 2003
Posts: 325
Location: dallas , tx
Followers: 1

Kudos [?]: 9 [0], given: 0

I got the same...a^2 -b^2/2
_________________

shubhangi

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