Thread: Which Quadrant?

In which quadrant is P(x,y) located if xy < 0 and x + y < 0?

MY WORK:

For xy > 0, I figured that for this to be true, both x and y must be positive values.

In other words, x and y cannot be 0 and negative.

For x + y < 0, one of the variables must be bigger than the other and negative.

I don't know where to go with this question in order to find the quadrant.

Originally Posted by sharkman

In which quadrant is P(x,y) located if xy < 0 and x + y < 0?

MY WORK:

For xy > 0, I figured that for this to be true, both x and y must be positive values.

In other words, x and y cannot be 0 and negative.

For x + y < 0, one of the variables must be bigger than the other and negative.

I don't know where to go with this question in order to find the quadrant.

Given , What if and ? Then . So x and y can also be negative! (this now tells us P(x,y) is either in the first or third quadrant)

Then it follows that . This satisfies the conditions of falling into the third quadrant.

Does this make sense?

Originally Posted by Chris L T521

Given , What if and ? Then . So x and y can also be negative! (this now tells us P(x,y) is either in the first or third quadrant)

Then it follows that . This satisfies the conditions of falling into the third quadrant.

Does this make sense?

Very easily explained.