1. Warm up Write the equation of a line when given: m = -1 b = ½3.

2. Skills Check

3. Writing Equations of Lines
Day 2

4. Essential Question
What’s the equation of a line given the slope and a point on the line?
What’s the equation of a line given two points on the line?

5. I. How to Write an Equation of a Line Given m and a point on the line.
1. Write down y = mx + b
2. Substitute slope for m and the point for (x, y).
Solve for b.
Substitute m and b back into the equation.

6. Write the equation of the line given m and a point
Ex 1: m = Point: (2, 3)
y = mx + b
3 = 2 (2) + b
b = -1
y = 2x – 1

7. Write the equation of the line given m and a point
Ex 2: m = ½ Point: (4, -3)
y = mx + b
-3 = ½ (4) + b
b = -5
y = ½ x – 5

8. Write the equation of the line given m and a point
Ex 3: m = Point: (-5, 3)
y = mx + b
3 = -2 (-5) + b
b = -7
y = -2 x – 7

9. Write the equation of the line given m and a point
Ex 4: m = 4 Point: (1, 4)
y = 4x

10. y = ½ x – 1.5 Ex 5: m = ½ Point: (-1, -2)
Write the equation of the line given m and a point
Ex 5: m = ½ Point: (-1, -2)
y = ½ x – 1.5

11. Write the equation of the line given m and a point
Ex 6: m = und Point: (3, 6)
X=3

12. IV. How to Write an Equation of a Line Given TWO points
Write down y = mx + b.
Use the slope formula to find m.
Pick one of the ordered pairs & substitute slope for m and the point (x, y).
Solve for b.
Substitute m and b into the equation.

13. Equation of a Line - Given 2 points
Ex: 7 (2, 3) and (4, 5)
y = mx + b
3 = 1(2) + b
b = 1
y = x + 1

14. Equation of a Line - Given 2 points
Ex: 8 (2, 3) and (-4, 15)
y = mx + b
3 = -2(2) + b
b = 7
y = -2x + 7

15. Equation of a Line - Given 2 points
Ex: 9 (2, 2) and (0, 4)
y = mx + b
2 = -1(2) + b
b = 4
y = -x + 4

16. Equation of a Line - Given 2 points
Ex: (2, 3) and (1, 4)
y = -x + 5

17. Equation of a Line - Given 2 points
Ex: (4, 5) and (5, 2)
y = -3x + 17

18. Equation of a Line - Given 2 points
Ex: (5, -3) and (7, 11)
y = 7x -38

19. Front of Worksheet Only do #6-10
Classwork
Front of Worksheet
Only do #6-10

20. Homework
Back of Worksheet