1. Objective: graph points and lines on the coordinate plane
Chapter 1
Algebra Toolbox
1-8 Graphing on a Coordinate Plane
Objective: graph points and lines on the coordinate plane

2. Agenda
Warm Up
Lesson Presentation
Practice Activity
Quiz

3. Warm Up
Find the values for y by substituting 1, 3, 5, and 7 for x.
1. y = 2x  3
1, 3, 7, 11
2. y = 4x + 1
5, 13, 21, 29
3. y = 5x  5
0, 10, 20, 30

4. Learn to graph points and lines on the coordinate plane.

5. Vocabulary coordinate plane x-axis y-axis x-coordinate y-coordinate
origin
graph of an equation

6. The coordinate plane is like a map formed by two number lines, the x-axis and the y-axis, that intersect at right angles.
Ordered pairs are the locations, or points, on the map. The x-coordinate and y-coordinate of an ordered pair tell the direction and number of units to move.
y-coordinate move up or down
x-coordinate move right or left
(x, y)

7. To plot an ordered pair, begin at the origin, the point (0, 0), which is the intersection of the x-axis and the y-axis.
The first coordinate tells how many units to move left or right; the second coordinate tells how many units to move up or down.

8. x y
(2, 3)
move right 2 units
(2, 3)
move up 3 units
(0, 0)
origin
The sign of a number indicates which direction to move.
Positive: up or right
Negative: down or left
Helpful Hint

9. Finding the Coordinates of Points on a Plane
Example 1:
Finding the Coordinates of Points on a Plane
Give the coordinates of each point. x y
(1, 3)
Point R is _______.
1 unit right, 3 units up R S T U
(0, –4)
Point S is _______.
0 units right, 4 units down
(–2, 2)
Point T is _______.
2 units left, 2 units up
(–3, 0)
Point U is _______.
3 units left, 0 units up

10. Give the coordinates of each point.
Try This: Example 1
Give the coordinates of each point. x y
(0, 2)
Point J is _______. K
0 units right, 2 units up J
(2, 0)
Point M is _______.
2 units right, 0 units up M
(–1, 4)
Point K is _______. P
1 unit left, 4 units up
(–3, –2)
Point P is _______.
3 units left, 2 units down

11. Example 2: Graphing Points on a Coordinate Plane
Graph each point on the coordinate plane. Label the points A-D. x y C A
A. (3, 4)
B. (4, 0)
right 3, up 4
right 4, up 0
C. (–4, 4)
D. (–1, –3) B
left 4, up 4
left 1, down 3 D

12. Graph each point on the coordinate plane. Label the points A-D.
Try This: Example 2
Graph each point on the coordinate plane. Label the points A-D. x y C A
A. (2, 4)
B. (2, 0)
right 2, up 4
right 2, up 0
C. (–2, 4)
D. (–1, –1) D B
left 2, up 4
left 1, down 1

13. The graph of an equation is the set of all ordered pairs that are solutions of the equation.

14. Example 3A: Graphing an Equation
Complete the table of ordered pairs. Graph the equation on a coordinate plane. x y
A. y = 3x
x 3x y (x, y)
3(0)
(0, 0) 1
3(1) 3
(1, 3) 2
3(2) 6
(2, 6) 3
3(3) 9
(3, 9)

15. Example 3B: Graphing an Equation
Complete the table of ordered pairs. Graph the equation on a coordinate plane. y
B. y = 2x – 3
x 2x – 3 y (x, y)
2(0) – 3 –3
(0, –3) x 1
2(1) – 3 –1
(1, –1) 2
2(2) – 3 1
(2, 1) 3
2(3) – 3 3
(3, 3)

16. Try This: Example 3A
Complete the table of ordered pairs. Graph the equation on a coordinate plane. x y
A. y = 2x
x 2x y (x, y)
2(0)
(0, 0) 1
2(1) 2
(1, 2) 2
2(2) 4
(2, 4) 3
2(3) 6
(3, 6)

17. Try This: Example 3B
Complete each table of ordered pairs. Graph each equation on a coordinate plane. y
B. y = 3x – 4
x 3x – 4 y (x, y)
3(0) – 4 –4
(0, –4) x 1
3(1) – 4 –1
(1, –1) 2
3(2) – 4 2
(2, 2) 3
3(3) – 4 5
(3, 5)

18. Give the coordinates of each point.
Lesson Quiz: Part 1
Give the coordinates of each point.
1. A
2. B
Graph each point on the given coordinate plane. Label points C, D.
3. C (5, –2)
4. D (0, 4) x y A B D
(2, 0)
(3, 4) C

19. Complete the table. Graph the equation on the given coordinate plane.
Lesson Quiz: Part 2
Complete the table. Graph the equation on the given coordinate plane.
5. y = 4x – 3 y
(2, 5) x
4x – 3 y
(x, y) 1 2
4(0)  3
4(1)  3
4(2)  3 3 1 5
(0, 3)
(1, 1)
(2, 5)
(1, 1) x
(0, 3)

20. Let’s try some!