2. 5.3 – Writing Linear Equations Given Two Points

3.  Today we will learn how to: ◦ Write an equation of a line given two points on the line ◦ Use a linear equation to model a real-life problem

4.  So far in this chapter, we were always given the slope  Now, we will have to first find the slope  Use the formula from Chapter 4

5.  Example 1 Write an equation of the line that passes through the points (-3, 1) and (5, 5).

6. WRITING AN EQUATION OF A LINE GIVEN TWO POINTS 1. Find the slope. Substitute the coordinates of the two given points into the formula for slope, 2. Find the y-intercept. Substitute the slope m and the coordinates of one of the points into the slope-intercept form,, and solve for the y-intercept, b.

7. WRITING AN EQUATION OF A LINE GIVEN TWO POINTS (cont.) 3. Write an equation of the line. Substitute the slope m and the y-intercept b into the slope-intercept form,.

8.  Example 2 Write an equation of the line that passes through the points (4, 9) and (1, 6).

9.  Example 3 Write an equation of the line that passes through the points (-2, -3) and (0, 3).

10. HOMEWORK Page 288 #18 – 44 even

11.  Example 3 For science class, you need to know the Celsius equivalent of a normal room temperature of 70º F. You know that Celsius temperature is linearly related to Fahrenheit and Celsius temperatures of the freezing and boiling point of water. Freezing point: 32ºF, OºC Boiling point: 212ºF, 100ºC Estimate the Celsius equivalent of normal room temperature.

12. Homework Page 289 #45 - 52