# Algebra 1 Companion Book, Vol 1 – Summer Edition

1.2.4 Introduction to Functions (continued) Example 2 Locating Points in the Coordinate Plane The x - and y -axes divide the coordinate plane into four regions called quadrants.

All points in quadrant I have positive x - and y -coordinates. All points in quadrant II have a negative x -coordinate and a positive y -coordinate. All points in quadrant III have negative x - and y -coordinates. All points in quadrant IV have a positive x -coordinate and a negative y -coordinate. If a point is not in a quadrant, then it must be on either the x -axis, the y -axis, or at the origin.

Example 3 Art Application

An equation that contains two variables can be used as a rule to generate ordered pairs. Substituting any value for x will generate a corresponding y -value, thus generating the ordered pair ( x , y ). For example, consider the equation y = 2 x + 1. If x = 5, then y = 2(5) + 1 = 11, or the ordered pair (5, 11).

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