X and Y

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X and Y

by nicajvch » Sat May 22, 2010 3:02 pm
Are x and y both positive?

1) 2x-2y = 1
2) x/y > 1

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by live2win » Sat May 22, 2010 5:37 pm
IMO E

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by frank1 » Sat May 22, 2010 6:54 pm
E

2x-2y = 1

if y is negative and x is negative it still can full fill this condition

2) x/y > 1
even if both are negative condition is met

so E

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by clock60 » Sun May 23, 2010 3:12 am
nicajvch wrote:Are x and y both positive?

1) 2x-2y = 1
2) x/y > 1
hi guys
don`t you think that the answer should be C
my thinking
(1) 2x-2y=1 insufficient but some operations
2x=1+2y
x=1/2+y

(2) x/y>1 insufficient as both x,y can be +ve or -ve
but both

x/y-1>0
(x-y)/y>0

and fron st1 x=1/2+y

(1/2+y-y)/y>0, here we cancel y and left with
(1/2)/y>0
as 1/2>0 without proving so y>0 for whole fraction to be >0

and x=1/2+y, where y>0 so x must be >0 so
C