Jones105 wrote:
Is the point (x,y) in the fourth quadrant)?
(1) xy >0
(2) y > 0
I recently took a practice test with my iPhone software (GMAT Math ver 1.1) and got a question I don't altogether agree with. Can someone help me out here?
The software says 1 alone is sufficient, but I think you need both.
My reasoning is that x could be -2 and y=-2, in that case, xy = 4 > 0. That would put the point in the 3rd quadrant while 2,2 would also fulfill that and put it in the 1st quad. Therefore 1 alone shouldn't be enough to be conclusive.
thanks for any insights...
First quadrant both are positive (x,y)
Second quadrant x is negative and y is positive (-x, y)
Third quadrant both are negative (-x, -y )
Fourth quadrant x is positive and y is negative (x, -y)
Statement 1)
xy>0 means that x and y must be of the same sign. so either in first or third quadrant. we know for sure it is not in the fourth quadrant. Sufficient.
Statement 2)
y > 0 we know that the fourth quadrant has a negative y so we know for sure that is not in the fourth quadrant. Sufficient.
Answer choice D