Question

In 2012 your car was worth $10,000. In 2014 your car was worth $8,850. Suppose the value of your car decreased at a constant rate of change. Define a function f to determine the value of your car (in dollars) in terms of the number of years t since 2012.

Answer 1

Answer:

The function to determine the value of your car (in dollars) in terms of the number of years t since 2012 is:

$f(t) = 10000(0.9407)^t$

Step-by-step explanation:

Value of the car:

Constant rate of change, so the value of the car in t years after 2012 is given by:

$f(t) = f(0)(1-r)^t$

In which f(0) is the initial value and r is the decay rate, as a decimal.

In 2012 your car was worth $10,000.

This means that $f(0) = 10000$, thus:

$f(t) = 10000(1-r)^t$

2014 your car was worth $8,850.

2014 - 2012 = 2, so:

$f(2) = 8850$

We use this to find 1 - r.

$f(t) = 10000(1-r)^t$

$8850 = 10000(1-r)^2$

$(1-r)^2 = \frac{8850}{10000}$

$(1-r)^2 = 0.885$

$\sqrt{(1-r)^2} = \sqrt{0.885}$

$1 - r = 0.9407$

Thus

$f(t) = 10000(1-r)^t$

$f(t) = 10000(0.9407)^t$