1. Lesson 3-4 Equations of Lines FormEquationDescription Slope- Intercept m is the slope, b is the y-intercept Point-Slopem is the slope, (x 1, y 1 ) is a given point StandardA and B are not both 0. A, B, and C have a GCF of 1. A is usually non- negative. When finding the equation of a line, we need to be able to fill in the slope and the y- intercept.

2. Write an equation in slope-intercept form of the line with slope of 6 and y -intercept of –3. Answer: The slope-intercept form of the equation of the line is Slope-intercept form

3. Write an equation in slope-intercept form of the line with slope of –1 and y -intercept of 4. Answer:

4. Write an equation in point-slope form of the line whose slope is that contains (–10, 8). Simplify. Point-slope form

5. Answer: Write an equation in point-slope form of the line whose slope is that contains (6, –3).

6. Write an equation in slope-intercept form for a line containing (4, 9) and (–2, 0). Find the slope of the line. Slope formula Simplify.

7. Now use the point-slope form and either point to write an equation. Point-slope form Add 9 to each side. Using (4, 9): Distributive Property

8. Point-slope form Distributive Property Using (–2, 0): Simplify. Answer:

9. Write an equation in slope-intercept form for a line containing (3, 2) and (6, 8). Answer:

10. Write an equation in slope-intercept form for a line containing (1, 7) that is perpendicular to the line the slope of a line perpendicular to it is 2.

11. Point-slope form Distributive Property Add 7 to each side. Answer:

12. Write an equation in slope-intercept form for a line containing (–3, 4) that is perpendicular to the line

13. RENTAL COSTS An apartment complex charges $525 per month plus a $750 security deposit. Write an equation to represent the total annual cost A for r months of rent. For each month of rent, the cost increases by $525. So the rate of change, or slope, is 525. The y -intercept is located where 0 months are rented, or $750. Answer: The total annual cost can be represented by the equation Slope-intercept form

14. RENTAL COSTS An apartment complex charges $525 per month plus a $750 security deposit. Compare this rental cost to a complex which charges a $200 security deposit but $600 per month for rent. If a person expects to stay in an apartment for one year, which complex offers the better rate? First complex: Second complex: Simplify. Answer: The first complex offers the better rate: one year costs $7050 instead of $7400.

15. Answer: RENTAL COSTS A car rental company charges $25 per day plus a $100 deposit. a. Write an equation to represent the total cost C for d days of use. b. Compare this rental cost to a company which charges a $50 deposit but $35 per day for use. If a person expects to rent a car for 9 days, which company offers the better rate? Answer: The first company offers the better rate. Nine days cost $325 instead of $365.