#4.

The table shows the value in dollars of a motorcycle at the end of x years.

Number of years, x
Value, v(x) (dollars)
12 , 000
10 , 800
9 , 720
8 , 748
Which exponential function models this situation?

"v" left parenthesis, "x" , right parenthesis equals 12 , 000 left parenthesis, 1.1 , right parenthesis Superscript, "x" , Baseline
"v" left parenthesis, "x" , right parenthesis equals 12 , 000 left parenthesis, 0.9 , right parenthesis Superscript, "x" , Baseline
"v" left parenthesis, "x" , right parenthesis equals 10 , 800 left parenthesis, 1.1 , right parenthesis Superscript, "x" , Baseline
"v" left parenthesis, "x" , right parenthesis equals 10 , 800 left parenthesis, 0.9 , right parenthesis Superscript, "x" , Baseline

1 answer

To determine which exponential function models the situation, we need to analyze the values provided for the motorcycle after each number of years. The values provided in the table indicate a depreciation of the motorcycle's value.

The values provided are:

  • After 0 years: 12,000 (initial value)
  • After 1 year: 10,800
  • After 2 years: 9,720
  • After 3 years: 8,748

To find the correct exponential function, we can notice how much the value decreases over time.

  1. The value after 1 year is 10,800, which is a decrease from 12,000. \[ \frac{10800}{12000} = 0.9 \text{ (or a 10% decrease)} \]

  2. The value after 2 years of depreciation from 10,800: \[ \frac{9720}{10800} = 0.9 \text{ (another 10% decrease)} \]

  3. The value after 3 years from 9,720: \[ \frac{8748}{9720} = 0.9 \text{ (again, a 10% decrease)} \]

The value is consistently multiplying by 0.9 each year. Therefore, we can conclude that the motorcycle depreciates by 10% each year. The model for the value after \(x\) years would be given by the initial value multiplied by a decay factor.

This leads us to the following exponential function: \[ v(x) = 12000 \times (0.9)^x \]

From the options provided, the correct model is: "v(x) = 12,000 * (0.9)^x."