Exercise 1 Page 151

In an ( x, y) ordered pair, the first number tells us the x-coordinate of the point and the second number tells us the y-coordinate of the point. To graph ( - 3, 3), we first find -3 on the x-axis and make a mental note of this grid line. The x-coordinate -3 tells us to move 3 units to the left of the origin — the negative horizontal direction.

Next, we find 3 on the y-axis and follow this grid line until it collides with the grid line from our x-coordinate. The y-coordinate 3 tells us to move 3 units up from the origin — the positive vertical direction.

The point ( - 3, 3) lies on the point at which these two grid lines intersect.

Extra

Quadrants of the Coordinate Plane

One common way that mathematicians describe points on a coordinate plane is by naming the quadrant in which the point lies. There are four quadrants and they are divided by the x- and y-axes.

The four quadrants are named using numbers. For example, the quadrant containing the positive x- and y-coordinates is either called Quadrant (I), the first quadrant, or Q1.