Ps question I got..

[accounts]

If x>y>0, and (x+y)^2=8xy, (x+y)/(x-y)=?

(A) 2^1/2
(B) 3^1/2
(C) 2
(D) 3
(E) 4

Correct Answer:A

[mundlia]

If x>y>0, and (x+y)^2=8xy, (x+y)/(x-y)=?

(A) 2^1/2
(B) 3^1/2
(C) 2
(D) 3
(E) 4


reply goes like this:
(x+y)^2=8xy
x^2 + y^2 +2xy = 8xy
or x^2 + y^2 -2xy = 4xy
or (x-y)^2 = 4xy

now (x+y)/(x-y) = ((x+y)^2 / (x-y)^2)^1/2
=(8xy)^1/2 / (4xy)^1/2
= 2^1/2

[accounts]

mundlia thanks.... this dint occur to me in 3 mints. was busy rationalizing the second expression.

[RonPurewal]

looks like the previous poster nailed this one.

i've gotta say, this doesn't look anything like an official gmat problem -- it's way too hard. is this problem really from gmat prep?
if not, this is not the correct place to post it -- please note the content of each folder on the forum, and then post problems in the correct folder. thanks.