1. Algebra 3 Lesson 1.3 Objectives: SSBAT write the equation of a line given the slope and y-intercept. SSBAT write the equation of a line given the slope and a point on the line. SSBAT write the equation of a line given 2 points. Standards: M11.D.3.2.2

2. Warm-Up 1.3 Solve each for y. 13x + 5y = 7x – 2y + 14

3. Writing an Equation given the Slope and Y-intercept  Substitute the slope and y-intercept into the equation y = mx + b for m and b

5. 2. Slope is -9 and y-intercept is -4 m b y = -9x – 4

6. 3. Slope is 0 and y-intercept is 12 m b y = 0x + 12 y = 12

7. Point-Slope Form of an Equation of a Line Used to write the equation of a line given 1) A point on the line and the slope 2) 2 points on the line y - y 1 = m(x - x 1 ) Where m is the slope and (x 1, y 1 ) is a point on the line.

8. Writing the equation given the slope and a point on the line 1. Substitute the slope in for m and the point in for x 1 and y 1 into y – y 1 = m(x – x 1 ) 2. Put the equation in the correct form (slope- intercept or standard form  given in directions)

9. Examples: Write an equation with the given point and slope. Write your answer in slope-intercept form. 1. Slope is 5 and through (4, -2) m x 1 y 1 y – -2 = 5(x – 4) y + 2 = 5x – 20 y = 5x – 22 y – y 1 = m(x – x 1 )

10. 2. Slope is ½ and through (-8, 1) m x 1 y 1 y – 1 = ½(x - -8) y – 1 = ½ (x + 8) y – 1 = ½ x + 4 y = ½ x + 5

11. 3. Slope is and through (-1, 5) y – 5 = (x - -1) y – 5 = (x + 1)

12. 4. Slope is and through (0, 7) y – 7 = (x – 0)

14. 1. (8, -1) and (2, 5) y - y 1 = m(x - x 1 ) Write the equation of the line that goes through the 2 points. Write your answer in slope-intercept form.

15. 2. Through (4, -1) and (1, 5) Choose 1 of the points: (4, -1) y – -1 = -2(x – 4) y + 1 = -2x + 8 y = -2x + 7

16. 3. Through (5, 0) and (-3, 2) Choose one Point and Substitute. (5, 0) y – 0 = -¼(x – 5) y = -¼ x + 1.25

17. 4. Through (-3, -4) and (6, 11) Choose point: (-3, -4)

19. Write the equation of the line represented in the graph below.

20.  Graphic Organizer

21. On Your Own. 1.Write the equation of the line with a slope of ¾ and a y-intercept of -1. y = ¾ x – 1 2. Write the equation of the line with a slope of 4 and goes through the point (1, -3). Write your answer in slope-intercept form. y = 4x – 7

22. Homework Worksheet 1.3