1. Writing Linear Equations When Given a Point and the Slope
Teacher Twins©2014

2. Warm Up
y = -5x + 12
y = 3/4x - 11
y = -2
y = 2x

3. Writing Linear Equations When Given a Point and the Slope

4. What two things do I need to write an equation of a line?
Slope
and
y intercept

5. We will first do this by graphing.
Ex 1:Write an equation of a line that has a slope of 3 and goes through (2,3).
We will first do this by graphing.
Graph the point and then use the slope to create the line.

6. We have the slope. All we need is the y intercept.
Look at the graph to see where it crosses the y axis (y intercept)

7. The slope is 3 and the y intercept is -3.
The equation is y = 3x – 3.

8. Now let’s do this algebraically.
We will use the slope intercept equation to find the y intercept (b).
We were given slope = 3 and it goes through the point (2,3).
m = 3 and (2, 3) Substitute this information into
x, y slope intercept form.
y = mx + b 3 = 3(2) + b
Solve to find b = 6 + b
-6 -6
-3 = b

9. The slope is 3 and the y intercept is -3.
The equation is y = 3x – 3.

12. Pairs Work

13. Partner A __________________ Partner B____________________

14. Partner A __________________ Partner B____________________

15. Closure
Write an equation of a line that has a slope of -3/5 and goes through (10,-7).
y = -3/5x - 1