What is y in terms of x ?

Question

(1) 1/(x/y + y/x) = 1/2
(2) x/y - y/x = 0

Damager · Answer

1. 1/(x^2+y^2)/xy)=1/2
 2xy=x^2+y^2==> x^2+y^2-2xy=0

(x-y)^2=0==> x=y

2. x^2-y^2/xy=0==> x^2-y^2=0

(x-y)(x+y)=0

either x=y or x=-y

GK_Gmat · Answer

Solved it the same way to get answer A.

bmwhype2 · Answer

in (2) why cant we set x^2 = y^2
it would then be |x| = |y| where we take only the nonnegative root?

bmwhype2 · Answer

nevermind, we want the positive value of Y which yields |x|, which has two roots, -x and X. therefore insuff

Damager · Answer

(1) x^2+y^2-2xy=0==> (x-y)^2=0==> x=y suff
(2) x^2-y^2=0 x=+/- y insuff
 answer A

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