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If x does not equal 0, then [x +( 1/x)]^2 - [x -( 1/x)]^2 =

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Source: — Data Sufficiency |
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by cramya » Sat Dec 13, 2008 8:19 am
a^2-b^2 = (a+b) (a-b)

a= x+1/x b=x-1/x


(a+b) = x+1/x+x-1/x = 2x

(a-b) = x+1/x-(x-1/x)
= x+1/x-x+1/x
= 2/x

2x * 2/x = 4
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by ravikirancheni » Sun Dec 14, 2008 3:05 am
(a+b)^2 - (a-b)^2 = 4ab

So 4(x)(1/x) => 4.

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