unit 5 day 2

 Objective: "Students will write the linear equation of a line using data from a line of best fit, or given 2 points."

This is the equation for lines: 

To find the eqaution of a line when givin two points, it is actually quite simple if you know what you are doing.
First you need to know this equation: ( y2 - y1 )
                                                        ( x2 - x1 )
This means that when you have two data points such as (2,6) and (4,8) for example, you take the 8, since it is the second y point and 6 is the first y point, and the you minus 6 from 8. You then do the same for the bottom, so you would have 4 minus 2. After you do the subtracting, you should end up with a y value over an x value, so from our example you should have 2/2 (or 1). This would be the rise over run in our linear equation, so our equation would look like this so far: y = x. to find the y intercept, you need to plug in one of the two data points t into your eqation. I am going to choose the point (4,8). I would get 8 = 1(4), which would be 8 = 4. After you have this, you take the number to the left of your equal sign, and you subtract the number on the right from the number on the left. so our final equation would look like this: y = x +4.

Quiz:

1. Write the equation used for lines.

2. Find the slope of a line passing through these points. (6,8) and (-5,-3)

3. What does the "b" represent in the equation?

Answer Key

1. The equation used for lines is y = mx + b.

2. The correct slope is y = x, or one. 

3. The "b" in the linear equation represents the "y" intercept. 

We also commented on Jack's blog.