GMATprep: x!=-y

[nhai2003]

Can anyone please explain to me: x!=-y mean??????

in this question:

If x != -y, is (x-y)/(x+y) > 1
1. x>0
2. y<0

[SanjeevK]

x!=-y means x is not equal to y.
(x-y)/(x+y) > 1
=> (x-y)/(x+y) -1 > 0
or -2y/(x+y) > 0

a: x>0 insufficient because y can be + or -
b: y<0 insufficient because x can be + or - and x can be greater than or less than y

combining both a: and b:
if x>0 and y<0 and x>y we will have -2y/(x+y) > 0
if x>0 and y <0 and x < y, we will have -2y/(x+y) < 0
hence insufficient

IMO E

[DanaJ]

x! is usually 1*2*3*...*x - and this is called a factorial. For instance:

4! = 1*2*3*4

10! = 1*2*3*...*9*10

As a convention, we have that 0! = 1! = 1.

Factorials can only be positive numbers, i.e. there's no such thing as (-3)!. This is why I believe that you might have made a mistake in writing your problem....