1. 4-3 Point-Slope Form Goal:
Use the point-slope form to write an equation of a line.
Eligible Content:
A / A / A

2. Vocabulary Point-Slope Form – any linear equation in the form
y – y1 = m (x – x1) where y1, m and x1 are replaced by numbers.
Examples:
y – 7 = 3(x – 8)
y + 6 = -3(x – 7)
y – 2 = ½ (x + 3)

3. y – y1 = m (x – x1) y – = (x – ) y + 4 = 6 (x – 2)
Write the equation in point-slope form of the line that goes through the point (2, -4) and has a slope of 6. m
y – y1 = m (x – x1) y – = (x – ) y + 4 = 6 (x – 2) y x -4 2 6

4. Examples Write the equation in point-slope form. m = 2, (3, 6)
y – 6 = 2 (x – 3)
m = -4, (2, -1)
y + 1 = -4 (x – 2)
m = ½ , (-5, -3)
y + 3 = ½ (x + 5)
m = -6, (-6, 2)
y – 2 = -6 (x + 6)

5. Write the point-slope form of an equation for a line that passes through (4, –3) with a slope of –2.
A. y – 4 = –2(x + 3)
B. y + 3 = –2(x – 4)
C. y – 3 = –2(x – 4)
D. y + 4 = –2(x – 3)

6. Write the equation in point-slope form of the line that goes through the points (5, 7) and (2, -4).
Find slope:
Write BOTH equations:
y – 7 = (x – 5)
y + 4 = (x – 2)

7. Examples Write the equation in point-slope form. (3, 2), (1, 6)
y – 2 = -2 (x – 3) AND y – 6 = -2 (x – 1)
(-2, 4), (3, -1)
y – 4 = -1 (x + 2) AND y + 1 = -1 (x – 3)
(4, -7) , (2, -1)
y + 7 = -3 (x – 4) AND y + 1 = -3 (x – 2)

8. Practice
Page 235 #1-3
4. (5, 2) and (-3, 6)
5. (2, -1) and (-4, 8)

9. Rewriting in Slope-Intercept Form
Write each equation in slope-intercept form.
y – 4 = 3(x + 6)
y = 3x +22
y + 2 = -2(x – 7)
y = -2x + 12
y + 7 = ½ (x + 9)
y = ½ x – 2.5

10. Homework
Page 236 #12-18 even
#28-34 even