Big Ideas Math Algebra 1, 2015
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Big Ideas Math Algebra 1, 2015 View details
5. Analyzing Lines of Fit
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Exercise 8 Page 206

Make a table of the residual values and then graph them on a scatter plot.

No, see solution.

Practice makes perfect

Let's begin by making a table of the residual values.

x y y=-0.5x-2 y-value From Model Residual
4 -1 -0.5( 4)-2 -4 -1-(-4)= 3
6 -3 -0.5( 6)-2 -5 -3-(-5)= 2
8 -6 -0.5( 8)-2 -6 -6-(-6)= 0
10 -8 -0.5( 10)-2 -7 -8-(-7)= -1
12 -10 -0.5( 12)-2 -8 -10-(-8)= -2
14 -10 -0.5( 14)-2 -9 -10-(-9)= -1
16 -10 -0.5( 16)-2 -10 -10-(-10)= 0
18 -9 -0.5( 18)-2 -11 -9-(-11)= 2
20 -9 -0.5( 20)-2 -12 -9-(-12)= 3

Now we can create a scatter plot using the given x-values and our residuals. Remember, if the model is a good fit for the data, the scatter plot will be evenly distributed above and below the x-axis. Also, there will be no apparent patterns.

Scatter plot

This line of fit does not model the data well. It is not evenly distributed above and below the x-axis. We can see that the residual points form a U-shaped pattern, which suggests the data is not linear.