Pre-Algebra
1-8 Graphing on the Coordinate Plane1-8 Graphing on the Coordinate Plane
Pre-Algebra
Warm UpWarm Up
Problem of the DayProblem of the Day
Lesson PresentationLesson Presentation
Pre-Algebra
1-8 Graphing on the Coordinate Plane
Warm UpFind the values for y by substituting 1, 3, 5, and 7 for x.
1, 3, 7, 115, 13, 21, 290, 10, 20, 30
Pre-Algebra
1-8 Graphing on the Coordinate Plane
3. y = 5x 52. y = 4x + 11. y = 2x 3
Pre-Algebra
1-8 Graphing on the Coordinate Plane
Problem of the Day
Tomorrow will be four days after the day before Saturday. What is today?
Monday
Pre-Algebra
1-8 Graphing on the Coordinate Plane
Learn to graph points and lines on the coordinate plane.
Pre-Algebra
1-8 Graphing on the Coordinate Plane
Vocabularycoordinate planex-axisy-axisx-coordinatey-coordinateorigingraph of an equation
Pre-Algebra
1-8 Graphing on the Coordinate Plane
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.
(x, y)x-coordinate move right or left
y-coordinate move up or down
Pre-Algebra
1-8 Graphing on the Coordinate Plane
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.
Pre-Algebra
1-8 Graphing on the Coordinate Plane
(2, 3)
The sign of a number indicates which direction to move. Positive: up or right Negative: down or left
Helpful Hint
x
y
origin
(2, 3)move right 2 units
move up 3 units
(0, 0)
Pre-Algebra
1-8 Graphing on the Coordinate Plane
Additional Example 1: Finding the Coordinates of Points on a Plane
Give the coordinates of each point.
Point R is _______.(1, 3)
1 unit right, 3 units up
Point S is _______.(0, –4)
0 units right, 4 units down
Point T is _______.(–2, 2)
2 units left, 2 units up
Point U is _______.(–3, 0)
3 units left, 0 units up
x
y
R
S
T
U
Pre-Algebra
1-8 Graphing on the Coordinate Plane
Try This: Example 1
Give the coordinates of each point.
Point J is _______.(0, 2)
0 units right, 2 units up
Point M is _______.(2, 0)
2 units right, 0 units up
Point K is _______.(–1, 4)
1 unit left, 4 units up
Point P is _______.(–3, –2)
3 units left, 2 units down
x
y
J
P
K
M
Pre-Algebra
1-8 Graphing on the Coordinate Plane
Additional Example 2: Graphing Points on a Coordinate Plane
Graph each point on the coordinate plane. Label the points A-D.
A. (3, 4)right 3, up 4
B. (4, 0)right 4, up 0
C. (–4, 4)left 4, up 4
D. (–1, –3)left 1, down 3
x
y
A
B
D
C
Pre-Algebra
1-8 Graphing on the Coordinate Plane
Try This: Example 2
Graph each point on the coordinate plane. Label the points A-D.
A. (2, 4)right 2, up 4
B. (2, 0)right 2, up 0
C. (–2, 4)left 2, up 4
D. (–1, –1)left 1, down 1
x
y
A
BD
C
Pre-Algebra
1-8 Graphing on the Coordinate Plane
The graph of an equation is the set of all ordered pairs that are solutions of the equation.
Pre-Algebra
1-8 Graphing on the Coordinate Plane
Additional Example 3A: Graphing an Equation
Complete the table of ordered pairs. Graph the equation on a coordinate plane.
x
yA. y = 3x
x 3x y (x, y) 0
1
2
3
3(0) 0 (0, 0)
3(1) 3 (1, 3)
3(2) 6 (2, 6)
3(3) 9 (3, 9)
Pre-Algebra
1-8 Graphing on the Coordinate Plane
Additional Example 3B: Graphing an Equation
Complete the table of ordered pairs. Graph the equation on a coordinate plane.
x
y
B. y = 2x – 3
x 2x – 3 y (x, y) 0
1
2
3
2(0) – 3 –3 (0, –3)
2(1) – 3 –1 (1, –1)
2(2) – 3 1 (2, 1)
2(3) – 3 3 (3, 3)
Pre-Algebra
1-8 Graphing on the Coordinate Plane
Try This: Example 3A
Complete the table of ordered pairs. Graph the equation on a coordinate plane.
x
yA. y = 2x
x 2x y (x, y) 0
1
2
3
2(0) 0 (0, 0)
2(1) 2 (1, 2)
2(2) 4 (2, 4)
2(3) 6 (3, 6)
Pre-Algebra
1-8 Graphing on the Coordinate Plane
Try This: Example 3B
Complete each table of ordered pairs. Graph each equation on a coordinate plane.
x
y
B. y = 3x – 4
x 3x – 4 y (x, y) 0
1
2
3
3(0) – 4 –4 (0, –4)
3(1) – 4 –1 (1, –1)
3(2) – 4 2 (2, 2)
3(3) – 4 5 (3, 5)
Pre-Algebra
1-8 Graphing on the Coordinate Plane
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)
(3, 4)
(2, 0)
x
y
A
B D
C