Section 1 - Graphing Points and Lines

Graphing points is similar to placing points on a number line. The type of graph we will be using in this section is called a cartesian graph, and it is basically two number lines lain perpendicular to each other.

The two number lines are labeled x and y, x being horizontal and y being vertical. These are each called an axis. The two axes divide the space into four quadrants. Each quadrant is given a roman numeral. The quadrants are labeled in a counterclockwise order (see graphic). Points can be placed in any of these coordinates. Although finding the coordinate of the point can be confusing. A point's coordinates are written as (x,y), x being the coordinate on the x axis and y being the coordiante on the y axis. To find the x - coordinate, use the axis as a number line, where the intersection is 0 (the intersection is also called the origin), anything to the left is positive, anything to the right is negative. To find the y - coordinate, use the intersection as 0, and everything above it is positive, anything below is negative. Let's find the coordinate for point A, it is 1 on the x axis, and it is 2 on the y axis, so it's coordinates are (1,2). The coordinates must always have parenthesis around them. Now try B, it is -1 on the x axis and -2 on the y axis, so it's coordinates are (-1,-2). It is also a good idea to remember that the intersection of the axes (the origin), has the coordinates of (0,0).

Line is drawn by plotting two points, and connecting them with a line. A line always has a formula of y = mx + b. Where y and x are the y and x coordinates, m is the slope (rate of incline or decline) of the line, and b is where the line intersects the y axis. Remember this formula, it will be used in later sections.

Write the x coordinate for each point-

1) (-1,8)

2) (3,6)

3) (-5,-3)

Write the y coordinate for each point-

4) (5,-11)

5) (4,7)

6) (16,3)

Use this graph for numbers 7 - 11..

7) A

8) B

9) C

10) D

11) E