1. 4-5A Writing Equations in Point-Slope Form Algebra 1 Glencoe McGraw-HillLinda Stamper

2. In today’s lesson you will write an equation given the slope and a point in point-slope form. To write an equation with this given information you will need to use the formula for point-slope form. Memorize point-slope form Read as: y minus y sub one equals m times the quantity of x minus x sub one. Where does the point-slope form come from?

3. x y The subscript identifies a specific known point. It takes two points to determine a line. You do not know where the other point is located. In point-slope form, the unknown point will be represented by (x,y). Write the slope formula.

4. Transform this formula by undoing the denominator. Simplify. 1 Use Symmetric Property to move everything to the other side of the equal sign. Commute the m. Start with the adjusted slope formula (no sub twos). The result is point-slope form.

5. In order to use point-slope you must know the slope and one point.

6. How to write the equation of a line in point-slope form given one point and a graph. 2. Write the point-slope form. 1. Find the slope by walking the line using slope ratio. 3. Substitute the given coordinate and the slope. 4. Simplify (undo double sign/double parentheses).

7. Write the equation of the line in the graph in point-slope form given the point (–2,–4). x y (–2,–4) The equation is in point-slope form. Do not distribute the slope.

8. Write the equation of the line in the graph in point-slope form using the given point. x y (3,–1) Do not distribute the slope. Example 1 (3,–1) Example 2 (-1,5) x y (-1,5)

9. Write in point-slope form the equation of the line that passes through each point with the given slope. Do not distribute the slope. Example 3 (–1,–7), m = –5 Example 4 (–2,4), m = 3 Example 5 (–4,–3), m = –9 Example 6 (–2,0), m =

10. Write the equation of the line in the graph in point-slope form using the given point. x y (-3,3) The slope of a horizontal line is 0. Example 7 (-3,3) Example 8 (4,-2) x y (4,-2)

11. x y time (hours) distance (miles) (2.5,162.5) 25 50 12 Candace and her family are visiting her grandmother. After 2.5 hours in the car, they have traveled 162.5 miles. If the average speed of travel is 65 miles per hour, write the equation of the line in point- slope form. 0 75 100 125 150 175 200 225 3 4 5 Let x represent hours and y represent miles. The average speed of travel is the slope, so m = 65. Let = (2.5,162.5).

12. x y time (hours) distance (miles) (1.5,810) 100 12 Example 9 Charlie is flying from San Diego, California, to Washington D.C., for vacation. After 1.5 hours, his plane has traveled 810 miles. If the average speed of travel is 540 miles per hour, write the equation of the line in point-slope. 0 300 500 700 900 3 4 5 Let x represent hours and y represent miles.

13. 4-A11 Pages 223-225 # 14–24,45,62-72.

14. Study Guide Page 56.