In the MGMAT inequality book, it states that you can't simply isolate the X variable in the following equation, because it could be + or -:
xy<3y
Instead, it says you should factorize the equation:
xy-3y<0
=y(x-3)<0
Then it says, "y and x-3 have opposite signs"... where did they come up with that?
Isn't x-3<0, which means x<3 (meaning, it could be a positive or negative number...
And y<0, which means it's negative.
Why is the book saying that they have opposite signs? They MAY have opposite signs, but that's not definitive, right?
What would be the correct answer to the original question?
xy<3y
Instead, it says you should factorize the equation:
xy-3y<0
=y(x-3)<0
Then it says, "y and x-3 have opposite signs"... where did they come up with that?
Isn't x-3<0, which means x<3 (meaning, it could be a positive or negative number...
And y<0, which means it's negative.
Why is the book saying that they have opposite signs? They MAY have opposite signs, but that's not definitive, right?
What would be the correct answer to the original question?
