5.2 ­ Direct Variation.notebook
January 05, 2016
1/5: Warm Up
Find the missing coordinate given that the line between the two points has the given slope.
(x, 4) and (1, ­2); m = 1
5.2 ­ Direct Variation.notebook
January 05, 2016
Date: 1/5
5.2: Direct Variation
Direction Variation: When the ratio of two variables is constant.
Ex 1). Does the equation represent direction variation? If so, find the
constant of variation.
a) 4y = 5x
b) 2x + 3y = 6
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5.2 ­ Direct Variation.notebook
January 05, 2016
Ex 2). Write a direct variation equation.
a) Suppose y varies directly with x and y = 40 when x = 8. What direction
variation equation relates x and y? What is the value of y when x = 12?
b) Suppose y varies directly with x and y = 10 when x = ­2. What direct
variation equation relates x and y? What is the value of y when x = ­15?
c) Suppose n varies directly with p and n = 9 when p = 5. What direct
variation equation relates n and p? What is the value of n when p = 8?
d) Suppose v varies directly with k and v = ­6 when k = 14. What direct
variation equation relates v and k? What is the value of k when v = 8?
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5.2 ­ Direct Variation.notebook
January 05, 2016
Ex 3). Graph a direction variation equation.
Suppose $15 (US) is worth about $150 Mexican pesos.
a) What is the equation that relates US dollars x to Mexican pesos y?
b) What is the graph of the equation in part (a)? 4
5.2 ­ Direct Variation.notebook
January 05, 2016
What do all direct variation equations have in common?
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5.2 ­ Direct Variation.notebook
January 05, 2016
Ex 4). Writing a direct variation from a table.
For the data in the tables, does y vary directly with x? If it does, write
an equation for the direct variation.
a)
x
y
x
y
2
5
1 7
6
15
3 10
10 25
5 13
6
5.2 ­ Direct Variation.notebook
January 05, 2016
Homework:
pg. 304 #1 – 7, 10 – 32 (e)
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