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Pre-Algebra

Learn to identify and graph linear equations. Graphing Linear Equations. 11-1. Pre-Algebra. Graphing Linear Equations. 11-1. Pre-Algebra.

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Pre-Algebra

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  1. Learn to identify and graph linear equations. Graphing Linear Equations 11-1 Pre-Algebra

  2. Graphing Linear Equations 11-1 Pre-Algebra A linear equation is an equation whose solutions fall on a line on the coordinate plane. All solutions of a particular linear equation fall on the line, and all the points on the line are solutions of the equation. To find a solution that lies between two points (x1, y1) and (x2, y2), choose an x-value between x1 and x2and find the corresponding y-value.

  3. Graphing Linear Equations 11-1 Pre-Algebra Reading Math Read x1 as “x sub one” or “x one.”

  4. Graphing Linear Equations 11-1 Pre-Algebra If an equation is linear, a constant change in the x-value corresponds to a constant change in the y-value. The graph shows an example where each time the x-value increases by 3, the y-value increases by 2. 2 3 2 3 2 3

  5. Graphing Linear Equations 11-1 Pre-Algebra Example 1A: Graphing Equations Graph the equation and tell whether it is linear. A. y = 3x – 1 3(–2) – 1 –7 (–2, –7) 3(–1) – 1 –4 (–1, –4) (0, –1) 3(0) – 1 –1 3(1) – 1 2 (1, 2) (2, 5) 3(2) – 1 5

  6. Graphing Linear Equations 11-1 Pre-Algebra Example 1A Continued The equation y = 3x – 1 is a linear equation because it is the graph of a straight line and each time x increases by 1 unit, y increases by 3 units.

  7. Graphing Linear Equations 11-1 Pre-Algebra Example 1B: Graphing Equations Graph the equation and tell whether it is linear. B. y = x3 (–2)3 –8 (–2, –8) (–1)3 –1 (–1, –1) (0, 0) (0)3 0 (1)3 1 (1, 1) (2, 8) (2)3 8

  8. Graphing Linear Equations 11-1 Pre-Algebra Example 1B Continued The equation y = x3 is not a linear equation because its graph is not a straight line. Also notice that as x increases by a constant of 1 unit, the change in y is not constant. +7 +1 +1 +7

  9. 3x Graphing Linear Equations 11-1 4 Pre-Algebra Example 1C: Graphing Equations Graph the equation and tell whether it is linear. C. y = –

  10. 3x 3 Graphing Linear Equations The equation y = – is a linear equation because the points form a straight line. Each time the value of x increases by 1, the value of y decreases by or y decreases by 3 each time x increases by 4. 11-1 4 4 Pre-Algebra Example 1 Continued

  11. Graphing Linear Equations 11-1 Pre-Algebra Example 1D: Graphing Equations Graph the equation and tell whether it is linear. D. y = 2 2 2 (–2, 2) 2 2 (–1, 2) (0, 2) 2 2 2 2 (1, 2) (2, 2) 2 2 For any value of x, y = 2.

  12. Graphing Linear Equations 11-1 Pre-Algebra Example 1D Continued The equation y = 2 is a linear equation because the points form a straight line. As the value of x increases, the value of y has a constant change of 0.

  13. Graphing Linear Equations 11-1 Pre-Algebra Example 2: Sports Application A lift on a ski slope rises according to the equation a = 130t + 6250, where a is the altitude in feet and t is the number of minutes that a skier has been on the lift. Five friends are on the lift. What is the altitude of each person if they have been on the ski lift for the times listed in the table? Draw a graph that represents the relationship between the time on the lift and the altitude.

  14. Graphing Linear Equations 11-1 Pre-Algebra Example 2 Continued

  15. Graphing Linear Equations 11-1 Pre-Algebra Example 2 Continued

  16. Graphing Linear Equations 11-1 Pre-Algebra Example 2 Continued The altitudes are: Anna, 6770 feet; Tracy, 6640 feet; Kwani, 6510 feet; Tony, 6445 feet; George, 6380 feet. This is a linear equation because when t increases by 1 unit, a increases by 130 units. Note that a skier with 0 time on the lift implies that the bottom of the lift is at an altitude of 6250 feet.

  17. Graphing Linear Equations 11-1 Pre-Algebra A linear equation is an equation whose solutions fall on a line on the coordinate plane. All solutions of a particular linear equation fall on the line, and all the points on the line are solutions of the equation. To find a solution that lies between two points (x1, y1) and (x2, y2), choose an x-value between x1 and x2and find the corresponding y-value.

  18. Graphing Linear Equations 11-1 Pre-Algebra Reading Math Read x1 as “x sub one” or “x one.”

  19. Graphing Linear Equations 11-1 Pre-Algebra If an equation is linear, a constant change in the x-value corresponds to a constant change in the y-value. The graph shows an example where each time the x-value increases by 3, the y-value increases by 2. 2 3 2 3 2 3

  20. Graphing Linear Equations 11-1 Pre-Algebra Try This: Example 1C Graph the equation and tell whether it is linear. C. y = x –8 (–8, –8) –6 (–6, –6) (0, 0) 0 4 (4, 4) (8, 8) 8

  21. The equation y = x is a linear equation because the points form a straight line. Each time the value of x increases by 1, the value of y increases by 1. Graphing Linear Equations 11-1 Pre-Algebra Try This: Example 1C Continued

  22. Graphing Linear Equations 11-1 Pre-Algebra Try This: Example 1D Graph the equation and tell whether it is linear. D. y = 7 7 7 (–8, 7) 7 7 (–4, 7) (0, 7) 7 7 7 7 (4, 7) (8, 7) 7 7 For any value of x, y = 7.

  23. Graphing Linear Equations 11-1 Pre-Algebra Try This: Example 1D Continued The equation y = 7 is a linear equation because the points form a straight line. As the value of x increases, the value of y has a constant change of 0.

  24. Graphing Linear Equations 11-1 Pre-Algebra Try This: Example 1A Graph the equation and tell whether it is linear. A. y = 2x + 1 2(–2) + 1 –3 (–2, –3) 2(–1) + 1 –1 (–1, –1) (0, 1) 2(0) + 1 1 2(1) + 1 3 (1, 3) (2, 5) 2(2) + 1 5

  25. Graphing Linear Equations 11-1 Pre-Algebra Try This: Example 1A Continued The equation y = 2x + 1is linear equation because it is the graph of a straight line and each time x increase by 1 unit, y increases by 2 units.

  26. Graphing Linear Equations 11-1 Pre-Algebra Try This: Example 1B Graphing the equation and tell whether it is linear. B. y = x2 (–2)2 4 (–2, 4) (–1)2 1 (–1, 1) (0, 0) (0)2 0 (1)2 1 (1, 1) (2, 4) (2)2 4

  27. Graphing Linear Equations 11-1 Pre-Algebra Try This: Example 1B Continued The equation y = x2 is not a linear equation because its graph is not a straight line.

  28. Graphing Linear Equations 11-1 Pre-Algebra Try This: Example 2 In an amusement park ride, a car travels according to the equation D = 1250t where t is time in minutes and D is the distance in feet the car travels. Below is a chart of the time that three people have been in the cars. Graph the relationship between time and distance. How far has each person traveled?

  29. Graphing Linear Equations 11-1 Pre-Algebra Try This: Example 2 Continued The distances are: Ryan, 1250 ft; Greg, 2500 ft; and Collette, 3750 ft.

  30. Graphing Linear Equations 11-1 Pre-Algebra Try This: Example 2 Continued y 5000 3750 Distance (ft) 2500 1250 x 1 2 3 4 Time (min) This is a linear equation because when t increases by 1 unit, D increases by 1250 units.

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