Question

For which points is the x-coordinate less than -1?

Answer 1

Answer:

Sometimes when answering a math question it helps to experiment a little.

Suppose the line is the X-axis. Every point on the X-axis has coordinates for some real number x so the product of the x and y coordinates is zero which satisfies "the product of the x-coordinate and the y-coordinate is less than or equal to zero".

Suppose the line is the Y-axis. Every point on the Y-axis has coordinates (0,y) for some real number y so the product of the x and y coordinates is zero which satisfies "the product of the x-coordinate and the y-coordinate is less than or equal to zero".

Now consider the lines y = x and y = -x. Take a few points on each of the lines and calculate the product of the x and y coordinates of each of the points you selected.