1. Do Now Write the slope-intercept equation of this line.

2. Writing Equations Given Slope and a Point 1)Substitute the slope and the coordinates of the point into y = mx + b. 2)Solve the equation for b. 3)Write the equation of the line using b.

3. Writing Equations – Type #2 Write an equation of the line that has a slope of 3 and goes through the point (2,1). To write an equation, you need two things: slope (m) = y – intercept (b) = We have to find the y-intercept!! Plug in the slope and ordered pair into y = mx + b 1 = 3(2) + b 3 ???

4. Writing Equations – Type #2 1 = 3(2) + b Solve the equation for b 1 = 6 + b -6 -6 -5 = b To write an equation, you need two things: slope (m) = y – intercept (b) = y = 3x - 5 3 -5

5. Example What is the equation of the line that has a slope of 3 and goes through (2, 3) ?

6. Writing Equations Given Two Points 1)Find the slope of the line. 2)Substitute the slope and the coordinates of one of the points into y = mx + b. 3)Solve the equation for b. 4)Write the equation of the line using b.

7. Writing Equations – Type #3 Write an equation of the line that goes through the points (4, 1) and (6, 2). To write an equation, you need two things: slope (m) = y – intercept (b) = We need both!! First, we have to find the slope. Plug the points into the slope formula. Simplify ???

8. Writing Equations – Type #3 Write an equation of the line that goes through the points (4, 1) and (6, 2). To write an equation, you need two things: slope (m) = y – intercept (b) = It’s now a Type #2 problem. Pick one of the ordered pairs to plug into the equation. Which one looks easiest to use? I’m using (6, 2). 2 = (6) + b ???

9. Writing Equations – Type #3 2 = (6) + b Solve the equation for b 2 = 3 + b – 3 – 1 = b To write an equation, you need two things: slope (m) = y – intercept (b) = – 1

10. Example What is the equation of the line that passes through ( – 2, 1) and (2, 3) ?

11. Write an equation of the line that goes through the points (0, 1) and (1, 4). 1.y = 3x + 4 2.y = 3x + 1 3.y = -3x + 4 4.y = -3x + 1

12. Graphing Lines In Slope – Intercept Form 1)Plot the y-intercept. 2)Write the slope as a fraction. * If it’s negative, put the negative on top. 3)Use the slope to find more points starting at the y- intercept. 4)Draw the line and label the equation.

13. Graph each line. 1) 2) 3)

15. Graph each line. 4) 5) 6)

17. Which is the graph of y = x + 2? 1. 2. 3. 4.