1. A LGEBRA 5.7 5.7 Point-Slope Form

2. L EARNING T ARGETS Language Goal Students will be able to explain how to graph a line and write a linear equation using point-slope form. Math Goal Students will be able to write a linear equation given two points. Essential Question Why is it important to have different forms to graph a line?

3. W ARM - UP

4. H OMEWORK C HECK

6. E XAMPLE 1: U SING S LOPE AND A P OINT TO G RAPH Steps are the same as if you were given a y- intercept Step 1: Plot the given point Step 2: Use the slope to move from the given point to the next point. Step 3: Connect the points.

7. E XAMPLE 1: U SING S LOPE AND A P OINT TO G RAPH

9. P OINT -S LOPE F ORMULA

10. E XAMPLE 2: W RITING L INEAR E QUATIONS IN P OINT -S LOPE FORM

12. E XAMPLE 3: W RITING L INEAR E QUATIONS IN S LOPE -I NTERCEPT F ORM Slope Intercept Form: y = mx + b Yesterday: Step 1: Find the y – intercept by... Plugging in the slope and the ordered pair. Solve for b. Step 2: Write the equation using the slope and b. Today: Step 1: Write the equation in point-slope form. Step 2: Write the equation in slope-intercept form by solving for y.

13. E XAMPLE 3: W RITING L INEAR E QUATIONS IN SLOPE -I NTERCEPT FORM

14. E XAMPLE 3: W RITING L INEAR E QUATIONS INS S LOPE -I NTERCEPT F ORM

15. E XAMPLE 4: U SING TWO POINTS TO WRITE AN EQUATION.

16. Write an equation in slope-intercept form for the line through the two points. A. (1, -4) and (3, 2) B. (4, -7) and (0, 5)

17. E XAMPLE 4: U SING TWO POINTS TO WRITE AN EQUATION. Write an equation in slope-intercept form for the line through the two points. C. (1, -2) and (3, 10) D. (6, 3) and (0, -1)

18. E XAMPLE 5: W ORD P ROBLEMS The cost to place an ad in a newspaper for one week is a linear function of the number of lines in the ad. The costs for 3, 5, and 10 lines are shown. Write an equation in slope-intercept form that represents the function. Then find the cost of an ad that is 18 lines long. Lines3510 Cost $13.5018.5031

19. E XAMPLE 5: W ORD P ROBLEMS At a different newspaper, the costs to place an ad for one week are shown. Write an equation in slope-intercept form that represents this linear function. Then find the cost of an ad that is 21 lines long. Lines3510 Cost $12.7517.2528.50

20. S UMMING I T U P ! Use the two points in the formula to find the slope. Then use the slope and one of the points to write the equation in point- slope form. If the slope is m and y –intercept is b, then the equation is y = mx + b Use the slope and the point to write the equation in point-slope form.

21. L ESSON Q UIZ