# 4.1- Plot Points in a Coordinate Plane

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4.1- Plot Points in a Coordinate Plane

Ordered pairs are used to locate points in a coordinate plane.
y-axis (vertical axis) 5 -5 5 x-axis (horizontal axis) -5 origin (0,0)

In an ordered pair, the first number is the x-coordinate
In an ordered pair, the first number is the x-coordinate. The second number is the y-coordinate. Graph. (-3, 2) 5 -5 5 -5

The x-axis and y-axis separate the coordinate plane into four regions, called quadrants.
II (-, +) I (+, +) III (-, -) IV (+, -)

Name the quadrant in which each point is located (-5, 4)
II III IV None – x-axis None – y-axis

Name the quadrant in which each point is located (-2, -7)
II III IV None – x-axis None – y-axis

Name the quadrant in which each point is located (0, 3)
II III IV None – x-axis None – y-axis

Example 1: Give the coordinates of the point.
(1,4) (-4,3) (0,3) (5,1) (-3,0) (1,0) (0,0) (0,-3) (-4,-4) (3,-4)

Example 2: Plot the point in a coordinate plane
Example 2: Plot the point in a coordinate plane Describe the location of the point.   a) A(-4,9) b) B(5,0) c) C(0,-8) d) D(7, -2) A(-4,9) B(5,0) D(7,-2) C(0,-8)

Example 3: Graph the function y = ½x + 1 with the
following values of x: -4, -2, 0, 2, and 4. Step 1: Make a table x y = ½x + 1 y -4 y = ½(-4) + 1 -1 -2 y = ½(-2) + 1 y = ½(0) + 1 1 2 y = ½(2) + 1 4 y = ½(4) + 1 3 x y = ½x + 1 y -4 y = ½(-4) + 1 -2 y = ½(-2) + 1 y = ½(0) + 1 2 y = ½(2) + 1 4 y = ½(4) + 1 x y = ½x + 1 y -4 y = ½(-4) + 1 -2 y = ½(-2) + 1 y = ½(0) + 1 2 y = ½(2) + 1 4 y = ½(4) + 1

What is the ordered pair for A?
5 (3, 1) (1, 3) (-3, 1) (3, -1) • A -5 5 -5

What is the ordered pair for C?
(0, -4) (-4, 0) (0, 4) (4, 0) 5 -5 5 • C -5

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