A function can be defined in the following six ways:
1. By a verbal rule: Total cost of roses when the unit price is $3. |
          | 2. As an equation: y = 3x. |           |
3. As a set of points: (0, 0), (1, 3), (2, 6), (3,9). |
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5. As a diagram:
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6. As a graph:
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CONCEPT CHECK: Out of the 6 representations, the one showing the best that the function's values are increasing is representation number: