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Graphing Using Intercepts 4.3 1.Given an equation, find the coordinates of the x - and y -intercepts. 2.Graph linear equations using intercepts.

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Presentation on theme: "Graphing Using Intercepts 4.3 1.Given an equation, find the coordinates of the x - and y -intercepts. 2.Graph linear equations using intercepts."— Presentation transcript:

1 Graphing Using Intercepts Given an equation, find the coordinates of the x - and y -intercepts. 2.Graph linear equations using intercepts.

2 Standard Form of a Linear Equation in 2-Variables A, B and C are integers. A ≥ 0 No fractions! A can’t be negative.

3 Is the given equation written in standard form? If not, rewrite it. A: Yes B: No No, can’t have fractions. 2x + 3y = 6 No, A can’t be negative. 4x - 3y = -7 No, x term must be written first. 5x – 2y = -3 Yes.

4 Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Objective 1 Given an equation, find the coordinates of the x - and y -intercepts.

5 The point where the graph crosses an axis is called an intercept. The point where a graph intersects the x-axis is called the x-intercept. (4, 0) The point where a graph intersects the y-axis is called the y-intercept. (0, -2) x-intercept (4, 0) y-intercept (0,  2) What do you notice about the intercepts?

6 To find an x-intercept:To find a y-intercept: 1. Let y = 0.1. Let x = Solve for x.2. Solve for y.

7 Find the x- and y-intercepts for 7x – 2y = 14 x-intercept: let y = 0 7x – 2y = 14 7x – 2(0) = 14 7x = 14 x = 2 x-intercept: (2, 0) y-intercept: let x = 0 7x – 2y = 14 7(0) – 2y = 14 –2y = 14 y = –7 y-intercept: (0, –7) Example 1 Always write an ordered pair!

8 Find the x- and y-intercepts for x-intercept: let y = 0 3x + 2(0) =18 3x = 18 x = 6 x-intercept: (6, 0) y-intercept: let x = 0 3(0) + 2y = 18 2y = 18 y = 9 y-intercept: (0, 9) Example 2

9 Find the x- and y-intercepts for x-intercept: let y = 0 y-intercept: let x = 0 Example 3

10 Find the x- and y-intercepts for x-intercept: let y = 0y-intercept: let x = 0 Example 4 0 = 6 Not true. Horizontal line. No x-intercept. 0x + y = 6 y = 6 (0, 6)

11 Find the x- and y-intercepts for x-intercept: let y = 0y-intercept: let x = 0 Example 5 0 = -4 Not true. Vertical line. No y-intercept. x + 0y = -4 x = -4 (-4, 0)

12 Objective 2 Graph linear equations using intercepts.

13 Graph: 7x – 2y = 14 From Example 1: x-intercept: (2, 0) y-intercept: (0, -7) 7x – 2y = 14 Example 6

14 Graph: x-intercept: (-4, 0) y-intercept: (0, 8) Example 7

15 Graph: x-intercept: (0, 0) y-intercept: (0, 0) Need another point. Choose a value for x or y and solve. Example 8 (5, -4)

16 Graph: Example 9 Equation has only a y. Line intersects only the y-axis. Horizontal line through -3.

17 Slide Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley What is the x-intercept for 3x – y = 6? a) (2, 0) b) (0, –6) c) (–6, 0) d) (0, 2)

18 Slide Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley What is the x-intercept for 3x – y = 6? a) (2, 0) b) (0, –6) c) (–6, 0) d) (0, 2)

19 Slide Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley What is the y-intercept for y = 2x – 6? a) (3, 0) b) (0, –6) c) (–6, 0) d) (0, 3)

20 Slide Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley What is the y-intercept for y = 2x – 6? a) (3, 0) b) (0, –6) c) (–6, 0) d) (0, 3)


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