Vince purchased a used car for $11,200. This make and model used car straight line depreciates to zero after 7 years. a. Identify the coordinates of the x- and y-intercepts for the depreciation equation. b. Determine the slope of the depreciation equation. c. Write the straight line depreciation equation that models this situation. d. Draw the graph of the straight line depreciation equation.

a) The problem statement tells you the value is 11200 at time 0, and the value is 0 at time 7 years. These are the "x" and "y" intercepts, assuming x represents years and y represents dollars of value.

x-intercept: 7
y-intercept: 11,200

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b) You know the value falls by 11200 in 7 years, so the slope is ...

m = -11200/7 = -1600

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c) In slope-intercept form, the equation can be written as ...

y = mx + b . . . . . . . . . where m is the slope, b is the y-intercept

y = -1600x + 11200

You can also write a linear equation using the intercepts directly:

x/x-intercept + y/y-intercept = 1

x/7 + y/11200 = 1

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d) Either of the above equations can be used to create the graph. It can be convenient to use the intercept form.