Introducing…. Section 5.5 Vocabulary

Introducing…. Section 5.5 Vocabulary Point-Slope form y – y1 = m (x – x1) • another way to show a line • use when you only have one point and the slope • m = slope, (x1, y1) = a point

Notes: Lesson 5-5 Objective: Write equations for lines using point-slope form

Linear Equations: So far, we know: 1. Standard form Ax + By = C x + 2y = 4 2. Slope-intercept form y = m x + b y = - ½ x + 2 m = slope b = y-intercept

3. Point – Slope Form y – y1 = m (x – x1) (x1, y1) = a given point m= slope This is easy to use if you know a point and the slope

Example 1: Write an equation for the line with a slope of -3 passing through (2, 4) Given: ( , ) m = 2 2 4 4 -3 -3 1. Write y – y1 = m (x – x1) 2. Substitute y – (x – ) = 3. Solve for y y – 4 = -3x + 6 +4 +4 y = -3x + 10

Example 2: Write an equation for the line with a slope of ¾ passing through (-8, 1) Given: ( , ) m = -8 -8 1 1 ¾ ¾ 1. Write y – y1 = m (x – x1) 2. Substitute y – (x – ) = 3. Solve for y y – 1 = ¼ x + 6 +1 +1 y = ¼ x + 7

Your turn. Leave each equation in slope-intercept form: 1. (1, -6) m = -1 2. (-3, -4) m = 0 y – y1 = m (x – x1) y – y1 = m (x – x1) y – -6 = -1 (x – 1) y – -4 = 0 (x – -3) y + 6 = -1x + 1 y + 4 = 0 -6 -6 -4 -4 y = -1x – 5 y = -4

Homework: Lesson 5-5, page 289 #15-26 all Put all answers into y = mx + b form! Chapter 5 Test: Wednesday Math lab today: Room A203 (north)

Introducing…. Section 5.5 Vocabulary