Question 157968
Data regarding the value of a particular color copier is represented in the graph. Find the rate of change of the value with respect to time,
(1, 3) and (3, 1)
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Basically, the two points provided are two points on a graph where the x-axis is time and the y-axis is "value of the color".
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So, when they are asking for "rate of change of the value with respect to time", they are asking of the slope between the two points.
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Slope between two points is:
(y2-y1)/(x2-x1)
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plugging in our two points:
(y2-y1)/(x2-x1)
(1-3)/(3-1) = -2/2 = -1 
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So, -1 is the rate of change.