| Direct Variation |
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When a value "y" increases as a value "x" increases, direct variation is said to be present. |
Below, "x" and "y" vary directly. As one increases, the other increases.
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Figure 1. |
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| Inverse Variation |
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"y" varies inversely with "x" if there is a nonzero constant such that xy = k. |
Here, "rate" and "time" vary inversely at a constant rate. As one increases, the other decreases:
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Figure 2. |
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