Unit 5 - Day 2

Unit 5

Day 2:

Students will write the linear equation of a line using data from a line of best fit, or given two points.

The linear equation of a line is an algebraic representation of a straight line, in which a line could be graphed from. I.E. y = 4x + 2

 Quiz

Figure 4

1. Write an equation for Figure 4.


2. Write an equation for Figure 5

3. Write an equation for Figure 6

Figure 5

Answers

1.First find 2 points on the graph (for example (1.5,2.5) and (8.5,4)) that were plotted on you're line of best fit. Use the equation m=y2-y1/x2-x1 that you learned on day one and the slope will be .21. Then place on of the sets of points into the y=mx+b equation. It might look something like this 2.5=.21(1.5) +b. To find b, simply multiply the .21 times 1.5 and subtract that from 2.5. You're final answer is y=.21x+2.185.
2.Use the points (2,2) and (3.5,4) and use the m=y2-y1/x2-x1 equation to find the slope which is 1.33. then put the first coordinates into the y=mx+b equation which should look like this 2=1.33(2)+b. Then find b and the final answer should look like y=1.33x-.66.

Figure 6

3. Using the points (.5,3.5) and (2.25,4.25) put them in the equation m=y2-y1/x2-x1 and the slope ends up being .43. then take the first set of coordinates and put them in the equation y=mx+b. It should look like 3.5=.43(.5)+b and now find b. The final equation should look like y=.43x+3.285.