The function is , where is the number of years after .

The numbers represent the years.

(a) Find , , and .

Substitute in .

.

Substitute in .

.

Substitute in .

.

represents the revenue for the year is million dollars.

represents the revenue for the year is million dollars.

represents the revenue for the year is million dollars.

(b) Find .

.

(c) Find , , and .

The function is , where is the number of years after .

The numbers represent the years.

Substitute in .

.

Substitute in .

.

Substitute in .

.

represents the revenue for the year is million dollars.

represents the revenue for the year is million dollars.

represents the revenue for the year is million dollars.

(d)

means 5 years prior to year .

In the model , represents five years after .

(e) 

The function is , where is the number of years after .

The function is , where is the number of years after .

An advantage in using the model instead of the model :

The model is used to determine the total projected world wide digital music revenue for the years after , where as when the model is used we can determine the revenue from the year . 

(a)

represents the revenue for the year is million dollars.

represents the revenue for the year is million dollars.

represents the revenue for the year is million dollars.

(b)

.

(c)

represents the revenue for the year is million dollars.

represents the revenue for the year is million dollars.

represents the revenue for the year is million dollars.

(d)

In the model , represents five years after .

(e)

The model is used to determine the total projected world wide digital music revenue for the years after , where as when the model is used we can determine the revenue from the year .