Day 2

Objective: Students will use the line of best fit to find the equation of lines.
Line of Best Fit is a straight line that best represents the data on a scatter plot.

   Chart
X         Y
0           3
 1          6
 2          9
 3          12
 4           15
                                      x y        x  y
Take 2 points, let's say 1,6 and 4,15.
y-y
x-x, so                                6-15= -9 % -3/-1, 3/1 = Slope of line of best fit
                                            1-4= -3
So, y=3/1 X + 3 is your equation of this line. 

Example: 

In a linear equation, there is a pattern in the lines.
All of the points connect in a straight line. 

Quiz: 
Question 1: What is the equation of a line that goes through the points 3, 10 and 8, 20?
Question 2: What is the equation of a line that goes through the points 1, 11 and 5, 55?
Question 3: What is the equation of a line that goes through the points 4, 30 and 8, 50?



Answer Key:
Q 1: y10 -y 20= -10
                                                               x3 -x 8= -5      Slope= 2/1 
Equation = Y= 2X + 4. You get 4 by putting 2 in the equation. 3x2=6, + 4= 10. You get 3, 10
Q 2 : y11 - y 55=  -44
         x1 - y 5= -4         reduce= 11/1 
Equation= Y= 11x 
Q 3 : 30 - 50= -20 
          4 - 8= -4   Reduce= 5/1
Equation= Y= 5x + 10. You get 10 from 4x5= 20, + 10= 30. 4, 30.