2.2 Direct Variation _1.notebook
February 08, 2012
2.2 Direct Variation
The post heights satisfy a relationship called direct variation. Some quantities are in a relationship where the ratio of corresponding values is constant.
Direct Variation: y = kx or The constant of variation is k.
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2.2 Direct Variation _1.notebook
February 08, 2012
For each function, determine whether y varies directly with x. If so, what is the constant of variation and the function rule?
C.
D.
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2.2 Direct Variation _1.notebook
February 08, 2012
For each function, determine whether y varies directly with x. If so, what is the constant of variation?
1. 3y = 7x
3. 5x + 3y = 0
2. 7y = 14x + 7
4. 3
2.2 Direct Variation _1.notebook
February 08, 2012
5. Suppose y varies directly with x, and y = 9 when x = ­ 15. What is y when x = 21? (Use a proportion to solve.)
6. Suppose y varies directly with x, and y = 15 when x = 3. What is y when x = 12? 4
2.2 Direct Variation _1.notebook
February 08, 2012
7. A salesperson's commission varies directly with sales. For $1000 in sales, the commission is $85. What is the commission for $2300 in sales?
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2.2 Direct Variation _1.notebook
February 08, 2012
The graph of a direct variation function is always a line through the origin.
8. What is the graph of ?
9. What is the graph of y = ­ 2x?
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2.2 Direct Variation _1.notebook
February 08, 2012
HW p. 71;1­23 odd, 25, 26, 31 ­ 45 odd
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2.2 Direct Variation _1.notebook
February 08, 2012
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