1. Algebra 1 Notes Lesson 5-4: Writing Equations in Slope-Intercept Form

2. Objectives
Write equations in slope intercept form given the slope and one point
Write equations in slope intercept form given two point

3. Example 1
Write an equation of a line that passes through (2, -3) with slope ½.
y = mx + b

4. Example 1
Write an equation of a line that passes through (2, -3) with slope ½.
y = mx + b y = ½ x + b

5. Example 1
Write an equation of a line that passes through (2, -3) with slope ½.
y = mx + b y = ½ x + b = ½ (2) + b

6. Example 1
Write an equation of a line that passes through (2, -3) with slope ½.
y = mx + b y = ½ x + b = ½ (2) + b = 1 + b

7. Example 1
Write an equation of a line that passes through (2, -3) with slope ½.
y = mx + b y = ½ x + b = ½ (2) + b = 1 + b
-1 -1

8. Example 1
Write an equation of a line that passes through (2, -3) with slope ½.
y = mx + b y = ½ x + b = ½ (2) + b = 1 + b = b

9. Example 1
Write an equation of a line that passes through (2, -3) with slope ½.
y = mx + b y = ½ x + b = ½ (2) + b = 1 + b = b y = ½ x – 4

10. Example 2
Write an equation of a line that passes through (-3, -4) and (-2, -8).
Slope:
y-intercept:

11. Write equation given two intercepts
x-int = 2 y-int = -5

12. Write equation given two intercepts
x-int = 2 y-int = -5 Sketch Graph

13. Write equation given two intercepts
x-int = 2 y-int = -5 Sketch Graph m =

14. Write equation given two intercepts
x-int = 2 y-int = -5 Sketch Graph m =

15. Write equation given two intercepts
x-int = 2 y-int = -5 Sketch Graph m = b =

16. Write equation given two intercepts
x-int = 2 y-int = -5 Sketch Graph m = b = -5

17. Write equation given two intercepts
x-int = 2 y-int = -5 Sketch Graph m = b = -5 y = x - 5

18. Homework
Worksheet!

19. Slope Intercept Form Story Problem Walk Through
Begin Day 2
Slope Intercept Form Story Problem Walk Through

20. Example 3
In the middle of the 1998 baseball season, Mark McGwire seemed to be on track for most runs batted in (RBI). After 40 games, McGwire had 45 RBIs. After 86 games, he had 87 RBIs. Write an equation in slope intercept form to estimate the number of runs batted in for any number of games that year.

21. Example 3
In the middle of the 1998 baseball season, Mark McGwire seemed to be on track for most runs batted in (RBI). After 40 games, McGwire had 45 RBIs. After 86 games, he had 87 RBIs. Write an equation in slope intercept form to estimate the number of runs batted in for any number of games that year.
Define Variables
x = y=

22. Example 3
In the middle of the 1998 baseball season, Mark McGwire seemed to be on track for most runs batted in (RBI). After 40 games, McGwire had 45 RBIs. After 86 games, he had 87 RBIs. Write an equation in slope intercept form to estimate the number of runs batted in for any number of games that year.
Define Variables
x = games
y= runs batted in

23. Example 3
In the middle of the 1998 baseball season, Mark McGwire seemed to be on track for most runs batted in (RBI). After 40 games, McGwire had 45 RBIs. After 86 games, he had 87 RBIs. Write an equation in slope intercept form to estimate the number of runs batted in for any number of games that year.
Define Variables 2 points, slope, or y-int
x = games
y= runs batted in

24. Example 3
In the middle of the 1998 baseball season, Mark McGwire seemed to be on track for most runs batted in (RBI). After 40 games, McGwire had 45 RBIs. After 86 games, he had 87 RBIs. Write an equation in slope intercept form to estimate the number of runs batted in for any number of games that year.
Define Variables 2 points, slope, or y-int
x = games (40,45)
y= runs batted in (86, 87)

25. Example 3 Define Variables 2 points, slope, or y-int x = games (40,45)
y= runs batted in (86, 87)
Find slope and y-int
m =

26. Example 3 Define Variables 2 points, slope, or y-int x = games (40,45)
y= runs batted in (86, 87)
Find slope and y-int
m =

27. Example 3 Define Variables 2 points, slope, or y-int x = games (40,45)
y= runs batted in (86, 87)
Find slope and y-int
m = = = 0.91

28. Example 3 Define Variables 2 points, slope, or y-int x = games (40,45)
y= runs batted in (86, 87)
Find slope and y-int
m = = = 0.91
y = 0.91x + b

29. Example 3 Define Variables 2 points, slope, or y-int x = games (40,45)
y= runs batted in (86, 87)
Find slope and y-int
m = = = 0.91
y = 0.91x + b
45 = 0.91(40) +b

30. Example 3 Define Variables 2 points, slope, or y-int x = games (40,45)
y= runs batted in (86, 87)
Find slope and y-int
m = = = 0.91
y = 0.91x + b
45 = 0.91(40) +b
45 = b

31. Example 3 Define Variables 2 points, slope, or y-int x = games (40,45)
y= runs batted in (86, 87)
Find slope and y-int
m = = = 0.91
y = 0.91x + b
45 = 0.91(40) +b
45 = b

32. Example 3 Define Variables 2 points, slope, or y-int x = games (40,45)
y= runs batted in (86, 87)
Find slope and y-int
m = = = 0.91
y = 0.91x + b
45 = 0.91(40) +b
45 = b
8.6 = b

33. Example 3 Define Variables 2 points, slope, or y-int x = games (40,45)
y= runs batted in (86, 87)
Find slope and y-int Write the equation
m = = = 0.91
y = 0.91x + b
45 = 0.91(40) +b
45 = b
8.6 = b

34. Example 3 Define Variables 2 points, slope, or y-int x = games (40,45)
y= runs batted in (86, 87)
Find slope and y-int Write the equation
m = = = y = 0.91x + 8.6
y = 0.91x + b
45 = 0.91(40) +b
45 = b
8.6 = b

35. Example 3
The record for RBIs in a season is Use your equation to decide if McGwire should break the record since there were 162 games that played that year.
Plug in the information for the correct variable

36. Example 3
The record for RBIs in a season is Use your equation to decide if McGwire should break the record since there were 162 games that played that year.
Plug in the information for the correct variable
y = 0.91(162) + 8.6

37. Example 3
The record for RBIs in a season is Use your equation to decide if McGwire should break the record since there were 162 games that played that year.
Plug in the information for the correct variable
y = 0.91(162) + 8.6
Solve for RBIs

38. Example 3
The record for RBIs in a season is Use your equation to decide if McGwire should break the record since there were 162 games that played that year.
Plug in the information for the correct variable
y = 0.91(162) + 8.6
Solve for RBIs Answer the question
y =

39. Example 3
The record for RBIs in a season is Use your equation to decide if McGwire should break the record since there were 162 games that played that year.
Plug in the information for the correct variable
y = 0.91(162) + 8.6
Solve for RBIs Answer the question
y = No, he should only have
156 RBIs

40. Example 3
In 2000, the cost of many items increased because of the increase in the cost of petroleum. In Chicago, a gallon of self-serve regular gasoline cost $1.76 in May and $2.13 in June. Write a linear equation to predict the cost of gasoline in any month in 2000, using 1 to represent January.

41. Example 3
In 2000, the cost of many items increased because of the increase in the cost of petroleum. In Chicago, a gallon of self-serve regular gasoline cost $1.76 in May and $2.13 in June. Write a linear equation to predict the cost of gasoline in any month in 2000, using 1 to represent January.
x = y =

42. Example 3
In 2000, the cost of many items increased because of the increase in the cost of petroleum. In Chicago, a gallon of self-serve regular gasoline cost $1.76 in May and $2.13 in June. Write a linear equation to predict the cost of gasoline in any month in 2000, using 1 to represent January.
x = Month y = price per gal.

43. Example 3
May = $1.76
June = $2.13

44. Example 3
May = $1.76 (5, 1.76)
June = $2.13

45. Example 3 May = $1.76 (5, 1.76) June = $2.13 (6, 2.13) Slope:
y-intercept:

46. Example 4
Use the equation to predict the cost of a gallon of gasoline in July.
$2.50 per gallon

47. Example 4
Use the equation to predict the cost of a gallon of gasoline in July.
$2.50 per gallon x 3,000 gallons = $7,500 in July

48. Example 4
Use the equation to predict the cost of a gallon of gasoline in July.
Do they need to add to the budget?

49. Example 4
Use the equation to predict the cost of a gallon of gasoline in July.
Do they need to add to the budget?
Yes, they need to add $500. Y

50. Vocabulary
Linear Extrapolation
- Linear Interpolation

51. Homework
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