GMAT prep

[rajt]

This should be easy but is driving me nuts.
if 0<x<y what is the value of (x+y)^2/(x-y)^2

1. x^2 +y^2 = 3xy
2. xy =3

[bww]

Is answer B?

1) not sufficient

2) plugging in xy=3 into the question...

(x^2+2(9)+y^2)/(x^2-2(9)+y^2)=
(x^2+y^2)/(x^2+y^2)=
=1

Am I missing something? Can anything be done with the information given in 1)?

[jayhawk2001]

This should be easy but is driving me nuts.
if 0<x<y what is the value of (x+y)^2/(x-y)^2

1. x^2 +y^2 = 3xy
2. xy =3

Is it A ?

1 - sufficient.

(x^2 + y^2 + 2xy) / (x^2 + y^2 - 2xy)
= 5xy / xy
= 5

2 - insufficient. Cannot simplify beyond (x^2 + y^2 + 6) / (x^2 + y^2 - 6)

[Cybermusings]

My answer is same as Jay....it should be A

Statement A:
(x+y)^2 =x^2+y^2+2xy
(x-y)^2=x^2+y^2-2xy
So 3xy+2xy / 3xy-2xy = 5xy/xy = 5

Statement B: Insufficient

Hence A

[bww]

oh wow. that's pretty clear--thanks!