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Graphing Lines and Linear Inequalities

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1 Graphing Lines and Linear Inequalities
Equations Drive on The Education Highway

2 Linear Equations and Graphing
1. Parts of a Coordinate Plane 2. Slope 3. Slope-intercept Form of a Linear Equation 4. Graphing by x- & y-intercepts.

3 Parts of a coordinate plane.

4 Click on the correct quadrant numbers. Correct answer = applause.
6 5 Quadrant Quadrant 4 I II III IV I II III IV 3 2 1 -1 Quadrant Quadrant -2 -3 I II III IV I II III IV -4 -5 -6 Lesson Start

5 Click on the correct axis names. Correct answer = clapping.
6 5 4 3 2 1 x-axis y-axis -1 -2 -3 -4 -5 -6 x-axis y-axis Lesson Start

6 Click on the point for the origin. Correct answer = clapping.
6 5 4 3 2 1 x -1 -2 -3 -4 -5 -6 Lesson Start y

7 Click on point (-3, 5). Correct point = applause.
6 5 4 3 2 1 x -1 -2 -3 -4 -5 -6 Lesson Start y

8 You chose a line segment instead of a point.
Go back and try again. INCORRECT ANSWER

9 INCORRECT ANSWER You chose point (5, -3).
Each ordered pair is in the form (x, y) -- it follows the alphabet in its internal order. You find the x value first, then you find the y value. Where they meet is the point. Go back and try again. INCORRECT ANSWER

10 Click on the correct ordered pair for the black point.
6 5 4 3 2 1 x -1 -2 -5/4 (-5, 4) -3 (4, -5) -4/5 -4 -5 -6 Lesson Start y

11 You did not choose an ordered pair.
Go back and try again. INCORRECT ANSWER

12 INCORRECT ANSWER You chose the ordered pair for the pale green point.
Remember: x comes before y in the alphabet and in an ordered pair. Go back and try again. INCORRECT ANSWER

13 Return to Main Menu. Return to Prior Problem. Continue to Next Lesson.

14 Slopes 1. What is a slope? 2. Slope formula 3. Types of slopes

15 Slope is the slant of a line. Slope = rise change in y’s
What is slope? Slope is the slant of a line. Slope = rise change in y’s run change in x’s Slope is a fraction/integer. Lesson Start

16 How to determine the slope when the line goes up.
1. Count the number of units up from the right point to the left point. 5 4 9 1 2 3 4 5 6 7 8 6 3 5 2 4 1 3 x 2 2. Put that number on top of the fraction line. -1 Slope = 6 1 -2 9 -3 -4 3, Count the number of units to the right. 4. Put that number under the fraction line. y Lesson Start

17 How to determine the slope when the line goes down.
1. Count the number of units down from right point to left point. 5 4 -1 3 -2 2 -3 1 -4 x 2. Put that number on top of fraction line. -5 -1 Slope = -6 -6 2 1 3 -2 3 -3 -4 3. Count the units to the right. y 4. Put that number under the fraction line. Lesson Start

18 Determine the slope of the line shown.
5 4 3 2 1 x -1 -2 -3 -4 -1/3 3/1 y -3/1 1/3 Lesson Start

19 The line does not go down.
Go back and try again. INCORRECT ANSWER Lesson Start

20 INCORRECT ANSWER The line does not rise 3 units,
then run 1 unit to the right. Go back and try again. INCORRECT ANSWER Lesson Start

21 Determine the slope of the line shown.
5 4 3 2 1 x -1 -2 -3 -4 -2/3 3/2 y -3/2 2/3 Lesson Start

22 INCORRECT ANSWER The line does not go up. Go back and try again.
Lesson Start

23 INCORRECT ANSWER The line does not rise -2 units,
then run 3 units to the right. Go back and try again. INCORRECT ANSWER Lesson Start

24 Slope Formula: m = (y1 - y2) (x1 - x2) where m = slope
and (x1, y1), (x2, y2) are points on the line. Lesson Start

25 1. Assign values as follows:
Example: Find the slope for a line with points (-3, 4) and (7, -2) on it. 1. Assign values as follows: (x1, y1) = (-3, 4) (x2, y2) = (7, -2) 2. Substitute them into the formula and solve. m = 4 - (-2) = = -3 Lesson Start

26 Find the slope of the line with points (5, 6) and (2, 9) on it.
1. (x1, y1) = (5, 6) (2, 9) Lesson Start

27 Find the slope of the line with points (5, 6) and (2, 9) on it.
1. (x1, y1) = (5, 6) 2. (x2, y2) = (5, 6) (2, 9) Lesson Start

28 Find the slope of the line with points (5, 6) and (2, 9) on it.
1. (x1, y1) = (5, 6) 2. (x2, y2) = (2, 9) 6 + 9 5 + 2 6 - 9 5 - 2 3. m = 5 - 2 6 - 9 5 + 2 6 + 9 Lesson Start

29 The slope formula is a case of subtraction
on top and bottom. Go back and try again. INCORRECT ANSWER Lesson Start

30 INCORRECT ANSWER You have your x’s and y’s upside down. Remember:
“Y’s guys are always in the skies!” Go back and try again. INCORRECT ANSWER Lesson Start

31 INCORRECT ANSWER You have your x’s and y’s upside down.
You are also adding when you need to subtract. Go back and try again. INCORRECT ANSWER Lesson Start

32 Find the slope of the line with points (5, 6) and (2, 9) on it.
1. (x1, y1) = (5, 6) 2. (x2, y2) = (2, 9) 3. m = = -3 = -1 Lesson Start

33 Find the slope of the line with points (7, 5) and (3, -4) on it. m =
5 - 4 = 1 = 4 5 - (-4) 9 5 - (-4) = 9 5 - (-4) = 9 Lesson Start

34 INCORRECT ANSWER You have your x’s and y’s upside down. Remember:
“Y’s guys are always in the skies!” Go back and try again. INCORRECT ANSWER Lesson Start

35 INCORRECT ANSWER It is not 5 - 4, it is 5 - (-4).
Go back and try again. INCORRECT ANSWER Lesson Start

36 You must start with the y and x from the first point and end with the y and x from the second point.
Go back and try again. INCORRECT ANSWER Lesson Start

37 Types of Slopes: 1. Positive and Negative Slopes
2. Special Types of Slopes 3. Determining Types of Slopes by Looking at Graphs of Lines 4. Determining Types of Slopes Algebraically. Lesson Start

38 Positive and Negative Slopes.
Type Graph Algebra Positive Up left to right. Positive Fraction SMILE Negative Down left to right Negative Fraction Frown Lesson Start

39 2 Special Types of Slopes Type Graphs Algebra
Zero Horizontal Line 0/a, a  0 Why, o y, do I look upon the horizon? Undefined Vertical Line a/0 No Slope Lesson Start

40 Determining Types of Slopes by Looking at Graphs of Lines
Lesson Start

41 + - Is the slope of the line positive, negative, zero, or undefined? 
5 4 3 2 1 x -1 -2 -3 -4 + - y Lesson Start

42 + - Is the slope of the line positive, negative, zero, or undefined? 
5 4 3 2 1 x -1 -2 -3 -4 + - y Lesson Start

43 + - Is the slope of the line positive, negative, zero, or undefined? 
5 4 3 2 1 x -1 -2 -3 -4 + - y Lesson Start

44 + - Is the slope of the line positive, negative, zero, or undefined? 
5 4 3 2 1 x -1 -2 -3 -4 + - y Lesson Start

45 Click on the line with the negative slope.
5 4 3 2 1 x -1 -2 -3 -4 y Lesson Start

46 Click on the line with the zero slope.
5 4 3 2 1 x -1 -2 -3 -4 y Lesson Start

47 Click on the line with the no slope.
5 4 3 2 1 x -1 -2 -3 -4 y Lesson Start

48 Click on the line with the positive slope.
5 4 3 2 1 x -1 -2 -3 -4 y Lesson Start

49 Determining Types of Slopes
Algebraically. Lesson Start

50 Is the slope of the line with the 2 points listed positive, negative, zero, or undefined?
Points (-3, 5) and (-9, -4) + - Lesson Start

51 Is the slope of the line with the 2 points listed positive, negative, zero, or undefined?
Points (3, 5) and (3, -4) + - Lesson Start

52 Is the slope of the line with the 2 points listed positive, negative, zero, or undefined?
Points (-3, -5) and (-9, -4) + - Lesson Start

53 Is the slope of the line with the 2 points listed positive, negative, zero, or undefined?
Points (-3, -4) and (-9, -4) + - Lesson Start

54 Return to Main Menu. Return to Prior Problem. Continue to Next Lesson.

55 Slope-intercept Form of a Linear Equation 1. Slope-intercept equation
2. Graphing by slope-intercept 3. Writing slope-intercept equations

56 Slope-intercept Form:
y = mx + b where m = slope and b = y-intercept. Lesson Start

57 Example: y = -1/2x + 4 -1/2 = m = slope 4 = b = y-intercept Lesson
Start

58 Graphing by Slope-intercept
1. Graphing lines with positive/negative slopes. 2. Graphing lines with zero or undefined/no slopes. Lesson Start

59 The Slope-intercept Song
You make the last number first. It’s either up or down. Make the slope in 2 numbers, Or you look like a clown. Top one’s up or down, And the bottom’s always right. You’d better do it well, Or you’ll get a fright. (Tune: “Hokey-Pokey”) Lesson Start

60 Graph y = -1/2x + 4 4. Draw a line through the 2 points you plotted. 1. Last number is 4, so go up 4 on the y-axis from the origin and plot a point. 2. Slope is already 2 numbers. Top one is -1, so go down 1 from the point you just plotted. 5 4 3 3 2 2 1 1 x -1 3. The bottom number is 2, so go 2 units to the right and plot a point. -2 -3 -4 y Lesson Start

61 Graph y = 2x - 3 1 1 2 4. Go 1 unit to the right and plot a point.
1. Last number is -3, so go down 3 units from the origin and plot a point. 2. The slope is only 1 number so put a 1 under the 2. 5 4 3 2 1 x 1 -1 3. Go up 2 from the point you just plotted. 5. Draw a line through the 2 points you plotted. 2 -2 -3 -4 y Lesson Start

62 Click on the graph for y = 2/3x - 2
5 4 3 2 1 x -1 -2 -3 -4 y Lesson Start

63 The slope is not negative.
Go back and try again. INCORRECT ANSWER Lesson Start

64 You graphed the last number on the x-axis instead of the y-axis.
Go back and try again. INCORRECT ANSWER Lesson Start

65 INCORRECT ANSWER Top number is 2, and the bottom is 3,
so you do not go up 3 and over 2. Go back and try again. INCORRECT ANSWER Lesson Start

66 Click on the graph for y = -4x + 3
5 4 3 2 1 x -1 -2 -3 -4 y Lesson Start

67 The slope is not positive.
Go back and try again. INCORRECT ANSWER Lesson Start

68 INCORRECT ANSWER The -4 is not the y-intercept,
nor is the 3 the x-intercept. Go back and try again. INCORRECT ANSWER Lesson Start

69 The -4 is the slope, not the x-intercept.
Go back and try again. INCORRECT ANSWER Lesson Start

70 Line with an undefined slope.
Two Special Graphs: Line with a zero slope And Line with an undefined slope. Lesson Start

71 “Why, o y, do I look upon the horizon?”
Line with a zero slope: y = # (no x) graphs as a horizontal line. “Why, o y, do I look upon the horizon?” Lesson Start

72 Graph the equation y = 2. x y Lesson Start 5 4 3 2 1
-1 -2 -3 -4 y Lesson Start

73 Line with an undefined/no slope: x = # (no y)
graphs as a vertical line. Lesson Start

74 Graph the equation x = -4. x y Lesson Start 5 4 3 2 1
-1 -2 -3 -4 y Lesson Start

75 Click on the graph for x = 3.
5 4 3 2 1 x -1 -2 -3 -4 y Lesson Start

76 You chose the graph for x = -3.
Go back and try again. INCORRECT ANSWER Lesson Start

77 The x = # (no y) line does not graph
as a horizontal line. Go back and try again. INCORRECT ANSWER Lesson Start

78 Click on the graph for y = -3½.
5 4 3 2 1 x -1 -2 -3 -4 y Lesson Start

79 The y = # (no x) line does not graph
as a vertical line. Go back and try again. INCORRECT ANSWER Lesson Start

80 You chose the graph for y = 3½.
Go back and try again. INCORRECT ANSWER Lesson Start

81 Writing Slope-intercept Equations:
1. When given a slope and the y-intercept. 2. When given a slope and one point on the line. 3. When given 2 points on the line. m = ¾, b = -1 m = -¼, (8, 3) (3, 7), (5, 12) Lesson Start

82 Substitute the slope and the y-intercept
Writing a slope-intercept equation when given a slope and the y-intercept. Substitute the slope and the y-intercept for the m and b in the equation. Example: m = ¾, b = -1 y = mx + b Slope-int. equation y = ¾x The new equation Lesson Start

83 1. Click on the correct equation for a line with
slope = 5/3 and y-intercept = 2. 5/3y = 2x y = 2x + 5/3 y = 5/3x + 2 y = -5/3x + 2 2. Click on the correct slope and y-intercept pair for y = 7x - 5. m = 7, b = -5 m = -5, b = 7 m = -7, b = 5 m = 1/7, b = -5 Lesson Start

84 1. Substitute the x, y, and m in the slope-intercept form.
Writing a slope-intercept equation when given a slope and a point on the line. 1. Substitute the x, y, and m in the slope-intercept form. 2. Solve for b. 3. Substitute the slope and the b in a clean slope-intercept form. Lesson Start

85 Example: Write the equation of the line with
slope = -¼ and point (8, 3). y = mx + b 3 = -¼(8) + b 1. Substitute the slope, x, and y in the equation. 2. Solve for b. 3 = -2 + b +2 +2 5 = b 3. Substitute the slope and b in the equation. y = -¼x + 5 Lesson Start

86 1. Click on the correct substitution for a line
with slope = 1/3 and point (5, 9). 9y = 5x + 1/3 9 = 1/3x + 5 9 = 1/3(5) + b 5 = 1/3(9) + b 2. Click on the correct equation for a line with slope = -2/3 and point (-6, 4). y = -2/3x - 6 y = -2/3 Y = -2/3x + 4 y = -2/3x Lesson Start

87 Writing a slope-intercept equation for a line with 2 points given:
1. Find the slope of the line. 2. Use that slope and the first point to find the y-intercept. 3. Substitute the slope and the y-intercept into the equation. Lesson Start

88 Continued on next screen.
Example: Write and equation for a line with points (3, 7) & (5, 12). m = (y1 - y2) (x1 - x2) m = = -5 = 5 1. Find the slope of the line. Continued on next screen. Lesson Start

89 Continued on next screen.
Write and equation for a line with points (3, 7) & (5, 12). m = 5/2 y = mx + b 7 = (5/2)(3) + b 2(7) = 2(15/2) + 2b 14 = b -1 = 2b  -1/2 = b 2 2 2. Use the slope and the first point to solve for the y-intercept. Continued on next screen. Lesson Start

90 Write and equation for a line with points (3, 7) & (5, 12).
m = 5/2, b = -1/2 3. Substitute the slope and the y-intercept for the m and the b in the equation. y = mx + b y = 5/2x - 1/2 Lesson Start

91 1. Click on the slope for a line with points (-2, 8) and (7, -5).
3 -9 13 -9 -9 13 13 9 2. Click on the y-intercept for a line with points (-2, 8) and (7, -5). 86 9 -5 86 13 46 9 Lesson Start

92 3. Click on the correct equation for a line
with points (3, 7) and (4, 8). y = 3x + 7 y = 3/4x + 8 y = x + 4 y = -x + 4 Lesson Start

93 Return to Main Menu. Return to Prior Problem. Continue to Next Lesson.

94 Graphing by x- and y-intercepts.
X-intercept: where the line crosses the x-axis. Y-intercept: where the line crosses the y-axis. x-intercept x y-intercept y

95 How to graph by x- & y-intercepts:
1. Cover the x term with your index finger and solve the resulting equation for y. 2. Go up or down on the y-axis from the origin that many units and plot a point. 3. Cover the y term with your index finger and solve the resulting equation for x. 4. Go left or right on the x-axis from the origin that many units and plot a point. 5. Draw a line through your points. Lesson Start

96 1. Cover the x term and solve for y.
Graph the line for 3x + 2y = 6. 1. Cover the x term and solve for y. 3x + 2y = 6. 2. Go up 3 units on the y-axis. 5. Draw a line through the points plotted. 5 4 3 2 2 y = 3 1 1 x 1 3. Cover the y term and solve for x. 3x + 2y = 6. 4. Go right 2 units on the x-axis. -1 -2 -3 -4 x = 2 y Lesson Start

97 1. Click on the correct intercepts for 3x - 4y = 24.
x-int: 8 y-int: 6 x-int: 8 y-int: -6 x-int: 6 y-int: 8 x-int: -6 y-int: 8 Lesson Start

98 2. Click on the graph of 3x - 6y = 12.
5 4 3 2 1 x -1 -2 -3 -4 y Lesson Start

99 3. Click on the correct equation for the line shown.
5 -9y - 6x = -36 4 4x + 6y = 36 3 2 1 x -1 6y + 4x = 36 -6x - 9y = -36 -2 -3 -4 y Lesson Start

100 Return to Main Menu. Return to Prior Problem. Continue to Next Lesson.

101 Graphing Linear Inequalities
Type of Line Solving Inequalities Where to Shade

102 Inequality Symbol Type of Line > or < Dotted Line Solid Line
How to Determine the Type of Line to Draw Inequality Symbol Type of Line > or < Dotted Line Solid Line

103 Choose the type of line for the inequality given.
1. y > 3x - 2 a. Solid b. Dotted 2. y > ¼x - 5 Lesson Start

104 Choose the inequality symbol for the line shown.
Lesson Start

105 Choose the inequality symbol for the line shown.
Lesson Start

106 For Positive, Negative, & Zero Slopes
Where to Shade For Positive, Negative, & Zero Slopes For Undefined or No Slopes

107 Where to Shade for Positive, Negative, and Zero Slopes:
The inequality must be in y  mx + b format.  can be: >, >, <, or <. Lesson Start

108 If the inequality is: Shade y > mx + b or Above the line
Below the line Lesson Start

109 Graph y > x - 2. 1. Graph the line y = x - 2. x
2. Since y >, shade above the line. y Lesson Start

110 Graph y < x - 2. 1. Graph the line y = x - 2. x
2. Since y <, shade below the line. y Lesson Start

111 Do you do anything different when the line is dotted rather than solid?
Lesson Start

112 Not Really Lesson Start

113 Graph y > x - 2. 1. Graph the line
y = x - 2, but make the line dotted. x 2. Since y >, shade above the line. y Lesson Start

114 Graph y < x - 2. 1. Graph the line
y = x - 2, but make the line dotted. x 2. Since y <, shade below the line. y Lesson Start

115 Graph y > -½x + 3 Type of line: Solid Dotted x y Lesson Start

116 Graph y > -½x + 3 Type of line: Solid Dotted x Shade ___ the line.
Above Below Lesson Start

117 Graph y > -½x + 3 Type of line: Solid Dotted x Shade ___ the line.
Above Below Lesson Start

118 Choose the correct inequality for the graph shown.
y < 1/3 x + 2 y < 1/3 x + 2 x y > 1/3 x + 2 y > 1/3 x + 2 y Lesson Start

119 Where to Shade for Undefined or No Slopes:
The inequality must be in x  # (no y) format.  can be: >, >, <, or <. Lesson Start

120 If the inequality is: Shade To the x > # or Right of the line
Left of the line Lesson Start

121 Graph x > -2 1. Draw a dotted vertical line at x = -2. x
2. Shade to the right of the line. y Lesson Start

122 Graph x < -2. 1. Graph the line X = -2. x
2. Shade to the left of the line. y Lesson Start

123 Graph x > 3. Choose type of line. Solid Dotted x y Lesson Start

124 Graph x > 3. Choose type of line. Solid Choose where to shade. Left
Right y Lesson Start

125 Graph x > 3. Choose type of line. Solid Choose where to shade.
Right y Lesson Start

126 Solving Inequalities You use the same algebraic methods as solving equations except when you multiply/divide both sides by the same negative number. In that case, you switch the direction of the inequality symbol. Lesson Start

127 Solve -3x - 2y < 12. -3x - 2y < 12 +3x +3x -2y < 3x + 12
y < -3/2 x - 6 > Lesson Start

128 Choose the correct inequality. 1. 2x + 5y > -10
Lesson Start


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