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500 PS

This topic has 2 member replies
dunkin77 Master | Next Rank: 500 Posts Default Avatar
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500 PS

Post Mon Apr 02, 2007 12:23 pm
Hi,

My answer to the attached question was B) but turned out that the correcr answer is A) - Could anyone please help?
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Post Fri Sep 29, 2017 1:29 pm
Given that x = sqrt(4xy - 4y^2)
square both side, we have
x^2 = 4xy - 4y^2
The above equation can be rewritten as
x^2 - 4xy - 4y^2= 0
Mathematically,
(x-2y)^2 = x^2 - 4xy - 4y^2
we can rewrite (x-2y)^2=0
square both side, we have x-2y = 0
i.e eliminating the square at the left hand side of the equation.
x-2y = 0
x=2y

option A is correct

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vk.neni Junior | Next Rank: 30 Posts Default Avatar
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27 Mar 2007
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Post Mon Apr 02, 2007 1:47 pm
It appears that the above equations can be reorganized a bit to make it easy for the further processing:

x = sqrt(4xy - 4y^2)

x^2 = 4xy - 4y^2

x^2 - 4xy + 4y^2 = 0

(x-2y)^2 = 0

x- 2y = 0

x = 2y

Answer is A

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