Question

The dollar value of a car is a function, f, of the number of years, t, since the car was purchased. The function is defined by the equation f(t)=12,000(3/4)^t.

A. How much was the car worth when it was purchased? Explain how you know.
B. What is f(2)? What does this tell you about the car?
C. About when was the car worth $6,000? Explain how you know.

Answer 1

1.) 12000

2.) 6750

3.) 2.41

Explanation:

Given the Equation :

f(t)=12,000(3/4)^t. ; where, t = time ; f(t) = worth of car at time, t

When, car was purchased, t = 0

t = 0

f(0) = 12000(3/4)^0

= 12000 * 1

= 12000

2.)

f(2) ; this mean the worth of the car after 2 years :

f(2)=12,000(3/4)^t.

12000(3/4)^2

12000 * 0.5625

= 6750

When car will be worth 6000

f(t) = 6000

f(t)=12,000(3/4)^t.

6000 = 12,000(3/4)^t

6000 / 12000 = (3/4)^t

1/2 = (3/4)^t

Take the log of both sides :

Log(0.5) = log(0.75)^t

log(0.5) = tlog(0.75)

- 0.301029 = - 0.124938t

t = - 0.301029 / - 0.124938

t = 2.4094

t = 2.41 years