Lesson 4­6 Model Direct Variation.notebook
October 27, 2016
P.O.D. Mixed Review
P. 259 #'s 48-50, 57-59
Lesson 4-6
Model Direct Variation
Objectives: Identify a direct variation equation, and graph it.
By: using the direct variation model y = ax
So that: we can solve and graph real-world problems.
We will succeed when we can model and graph distance problems.
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y
6
5
4
3
2
1
­6
­5
­4
­3
­2
­1
0
­1
x
1
2
3
4
5
6
­2
­3
­4
­5
­6
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P.O.D. (Day 2)
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P.O.D. (Day 2)
What is the value of x if Lines 1 and 2 are parallel?
What is the value of y for the line that has a slope of and passes through the points (3, 5) and (7, y)?
Line 1: (­2, ­5) and (0, 0)
Line 2: (x, 12) and (­3, 2)
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Lesson 4­6 Model Direct Variation.notebook
Two variables, x and y show direct variation if October 27, 2016
Which equations are direct variations? Identify the constant of variation.
Example:
The coefficient of x is called the constant of variation and
y is said to vary directly with x.
Compare this equation with Oct 30­4:19 PM
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Notice that a direct variation equation, is a linear equation in slope­intercept form, where Therefore, the line passes through the origin.
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Lesson 4­6 Model Direct Variation.notebook
October 27, 2016
y
6
5
4
3
2
1
­6
­5
­4
­3
­2
­1
x
0
­1
1
2
3
4
5
6
­2
­3
­4
­5
­6
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y
10
9
8
7
6
5
4
3
2
1
­10
­8
­6
­4
­2
0
­2
­3
­4
­5
­6
­7
­8
­9
­10
x
2
4
6
8
10
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The graph of a direct variation equation passes through the point (­4, 5). Write the direct variation equation and find the value of y when x = 20.
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Lesson 4­6 Model Direct Variation.notebook
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Ratios: The direct variation equation October 27, 2016
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can be written as So, in a direct variation, the
ratio of y to x is constant for all nonzero data pairs.
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Closing:
In what form is a direct variation equation written?
What is the constant of variation?
What does the graph of a direct variation look like?
How do you graph a direct variation?
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Lesson 4­6 Model Direct Variation.notebook
October 27, 2016
Homework
WS 4-6 Practice B:
#'s 2-34 even
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Lesson 4­6 Model Direct Variation.notebook
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Lesson 4­6 Model Direct Variation.notebook
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Lesson 4­6 Model Direct Variation.notebook
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October 27, 2016
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