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Lesson 1-3, 1-4 Represent Functions as Graphs; Graphing Linear Equations using Intercepts.

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Presentation on theme: "Lesson 1-3, 1-4 Represent Functions as Graphs; Graphing Linear Equations using Intercepts."— Presentation transcript:

1 Lesson 1-3, 1-4 Represent Functions as Graphs; Graphing Linear Equations using Intercepts.

2 Graph the function y=3x with domain 0,1,2,3,4. Step 1: Make an input-output table. Step 2: Plot a point for each ordered pair. Graph a function X01234 y036912

3 Practice Problems Graph the functions: 1) y=2x+3 Domain: 0,2,4,6,8 2) y=-2x-7 Domain: 1,2,3,4,5 3) y=-3/4x+6 Domain: 0,4,8,12,16 4) y= y=1/2x-4 Domain: 1,2,3,4,5 5) y=1/3x-3 Domain: 0,3,6,9,12

4 Write a function rule for a graph. See Graph Step 1: Make a table Step 2: Find a relationship between the inputs and outputs. Step 3: Write a function rule.

5 Helpful Hints to Writing Rules First, check for a common DIFFERENCE between x and y values. For example, x1347 y3569 The DIFFERENCE of every value of x and y is 2. Therefore, the rule is y=x+2.

6 Helpful Hints to Writing Rules Second, if no common difference is found, check for a COMMON MULTIPLIER. For example, x1234 y481216 Every value of x can be multiplied by 4 to get the values for y. Therefore, the rule is y=4x.

7 Helpful Hints for Writing Rules If no common difference or multiplier can be found, check for BOTH! For example, x1234 y471013 In the table above, there is no common difference between x and y. 4-1=3 but 7-2=5. Also, there is no common multiplier. 1x4=4, but 2x4≠7. Therefore, we check for BOTH, 1x3=3, then, 3+1=4. 3x3=9, then, 9+1=10. So, the rule is y=3x+1.

8 Lesson 1-4 Graph Using Intercepts Find x-intercept and y-intercept of the graph of 7x- 3y=21 Solution: To find x-intercept, sub 0 for y and solve for x. 7x-3y=21 7x-3(0)=21 x=21/7 or x=3 To find y-intercept, sub 0 for x and solve for y. 7x-3y=21 7(0)-3y=21 y=-21/3 or -7

9 Use a Graph to find Intercepts Find the x and y intercepts of the graph. The line crosses the x-axis at 2, therefore the x-intercept is 2. The line crosses the y-axis at -4, therefore the y-intercept is -4. (2,0) (0,-4)

10 Use Intercepts to Graph an Equation Graph 3x+2y=6. Label the points where the line crossed the axes. Step 1: Find the intercepts. 3x+2y=6 3x+2y=6 3x+2(0)=6 3(0)+2y=6 x=2 x-intercept y=3 y-intercept Step 2: Plot the points on a graph. X-int= (2,0) Y-int= (0,3) Step 3: Connect the points with a line. (0,3) (2,0)

11 Guided Practice Pg. 18 Problems 1-5 Assignment pg. 19 1-27 (odd only)


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