dabaobao wrote:
Is |x| = |y| ?
(1) x = –y
(2) x^2 = y^2
Question stem:- Is |x| = |y| ?
St1:- x = –y or, y=-x
1) if y>0 , then x<0 So, |x|=-x and |y|=y=-x implies that |x|=|y|
2) if y<0, then x>0 So, |x|=x and |y|=-y=x implies that |x|=|y|
Sufficient.
St2:-\(x^2 = y^2\)
Or, \(x^2-y^2=0\)
Or, (x+y)(x-y)=0
So, x+y=0 or x-y=0
x=-y Or, x=y
1) When x=-y ,as explained in st1(same as st1) |x|=|y|
2) When x=y or, when both x and y are equal in magnitude and posses same polarity, a) |x|=x=|y|=y (x,y>0) b)|x|=-x=|y|=-y (x,y<0)
Sufficient.
Ans. (D)
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Regards,
PKN
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