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Holt Algebra 1 5-7 Point-Slope Form Warm Up Find the slope of the line containing each pair of points. 1. (0, 2) and (3, 4) 2. (–2, 8) and (4, 2) 3. (3,

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Presentation on theme: "Holt Algebra 1 5-7 Point-Slope Form Warm Up Find the slope of the line containing each pair of points. 1. (0, 2) and (3, 4) 2. (–2, 8) and (4, 2) 3. (3,"— Presentation transcript:

1 Holt Algebra Point-Slope Form Warm Up Find the slope of the line containing each pair of points. 1. (0, 2) and (3, 4) 2. (–2, 8) and (4, 2) 3. (3, 3) and (12, –15) Write the following equations in slope-intercept form. 4. y – 5 = 3(x + 2) 5. 3x + 4y + 20 = 0

2 Holt Algebra Point-Slope Form Graph a line and write a linear equation using point-slope form. Write a linear equation given two points. Objectives

3 Holt Algebra Point-Slope Form In lesson 5-6 you saw that if you know the slope of a line and the y-intercept, you can graph the line. You can also graph a line if you know its slope and any point on the line.

4 Holt Algebra Point-Slope Form Example 1A: Using Slope and a Point to Graph Graph the line with the given slope that contains the given point. slope = 2; (3, 1)

5 Holt Algebra Point-Slope Form slope = ; (–2, 4) Example 1B: Using Slope and a Point to Graph Graph the line with the given slope that contains the given point.

6 Holt Algebra Point-Slope Form Example 1C: Using Slope and a Point to Graph Graph the line with the given slope that contains the given point. slope = 0; (4, –3)

7 Holt Algebra Point-Slope Form Check It Out! Example 1 Graph the line with slope –1 that contains (2, –2).

8 Holt Algebra Point-Slope Form If you know the slope and any point on the line, you can write an equation of the line by using the slope formula. For example, suppose a line has a slope of 3 and contains (2, 1). Let (x, y) be any other point on the line. 3(x – 2) = y – 1 y – 1 = 3(x – 2) Slope formula Substitute into the slope formula. Multiply both sides by (x – 2). Simplify.

9 Holt Algebra Point-Slope Form

10 Holt Algebra Point-Slope Form Example 2: Writing Linear Equations in Point-Slope Form Write an equation in point-slope form for the line with the given slope that contains the given point. A.B. C.

11 Holt Algebra Point-Slope Form Check It Out! Example 2 Write an equation in point-slope form for the line with the given slope that contains the given point. a. b. slope = 0; (3, –4)

12 Holt Algebra Point-Slope Form Example 3: Writing Linear Equations in Slope- Intercept Form Write an equation in slope-intercept form for the line with slope 3 that contains (–1, 4). Step 1 Write the equation in point-slope form: Step 2 Write the equation in slope-intercept form by solving for y.

13 Holt Algebra Point-Slope Form Check It Out! Example 3 Write an equation in slope-intercept form for the line with slope that contains (–3, 1). Add 1 to both sides.

14 Holt Algebra Point-Slope Form Check It Out! Example 3 Continued Write an equation in slope-intercept form for the line with slope that contains (–3, 1).

15 Holt Algebra Point-Slope Form Example 4A: Using Two Points to Write an Equation Write an equation in slope-intercept form for the line through the two points. (2, –3) and (4, 1)

16 Holt Algebra Point-Slope Form Example 4A Continued Write an equation in slope-intercept form for the line through the two points. (2, –3) and (4, 1)

17 Holt Algebra Point-Slope Form Example 4B: Using Two Points to Write an Equation Write an equation in slope-intercept form for the line through the two points. (0, 1) and (–2, 9)

18 Holt Algebra Point-Slope Form Example 4B Continued Write an equation in slope-intercept form for the line through the two points. (0, 1) and (–2, 9)

19 Holt Algebra Point-Slope Form Check It Out! Example 4a Write an equation in slope-intercept form for the line through the two points. (1, –2) and (3, 10)

20 Holt Algebra Point-Slope Form Check It Out! Example 4a Continued Write an equation in slope-intercept form for the line through the two points. (1, –2) and (3, 10)

21 Holt Algebra Point-Slope Form Check It Out! Example 4b Write an equation in slope-intercept form for the line through the two points. (6, 3) and (0, –1)

22 Holt Algebra Point-Slope Form Check It Out! Example 4b Continued Write an equation in slope-intercept form for the line through the two points. (6, 3) and (0, –1)

23 Holt Algebra Point-Slope Form Example 5: Problem-Solving Application The cost to stain a deck is a linear function of the deck s area. The cost to stain 100, 250, 400 square feet are shown in the table. Write an equation in slope-intercept form that represents the function. Then find the cost to stain a deck whose area is 75 square feet.

24 Holt Algebra Point-Slope Form Check It Out! Example 5 What if…? At a newspaper the costs to place an ad for one week are shown. Write an equation in slope-intercept form that represents this linear function. Then find the cost of an ad that is 21 lines long.

25 Holt Algebra Point-Slope Form Lesson Quiz: Part I Write an equation in slope-intercept form for the line with the given slope that contains the given point. 1. Slope = –1; (0, 9) 2. Slope = ; (3, –6) Write an equation in slope-intercept form for the line through the two points. 3. (–1, 7) and (2, 1) 4. (0, 4) and (–7, 2)

26 Holt Algebra Point-Slope Form Lesson Quiz: Part II 5. The cost to take a taxi from the airport is a linear function of the distance driven. The cost for 5, 10, and 20 miles are shown in the table. Write an equation in slope-intercept form that represents the function.


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