Math Is Fun Forum

nycguitarguy

Member

Registered: 2024-02-24

Posts: 549

Digital Music Revenues

The total projected worldwide digital music revenues R, in millions of dollars, for the years 2005 through 2010 can be estimated by the function

R(x) = 170.7x^2 + 1373x + 1080 where x is the number of years after 2005.

(a) Find R(0), R(3) and R(5),represents. Explain what each value represents.

(b) Find r = R(x- 5).

(c) Find r(5), r(8), and r(10), and explain what each value represents.

(d) In the model r, what does x represent?

Let me see.

Part A

I simply replace x with 0, 3, and 5 but I have no idea what each value represents.

Part B

Can you set it up for me?

Part C

I think r(5) represent the year 2005, r(8) represents the year 2008 and r(10) represents the year 2010.

You say?

Part D

I need the model r to guess what x represents.

Last edited by nycguitarguy (2024-04-23 05:44:28)

Bob

Administrator

Registered: 2010-06-20

Posts: 10,198

Re: Digital Music Revenues

Your answers in part (a) tell us the digital revenue (how much money was made) in the years x = 0, 3 and 5 which means the years 2005, 2007, 2009.

r(x) = R(x-5) = 170.7(x-5)^2 + 1373(x-5) + 1080 

The (c) answers should be the same as the (a) answers.

In this new model when x =  5 the year is 2005, so the new model is the same as the old except the start year is now 2000.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

nycguitarguy

Member

Registered: 2024-02-24

Posts: 549

Re: Digital Music Revenues

Your answers in part (a) tell us the digital revenue (how much money was made) in the years x = 0, 3 and 5 which means the years 2005, 2007, 2009.

r(x) = R(x-5) = 170.7(x-5)^2 + 1373(x-5) + 1080 

The (c) answers should be the same as the (a) answers.

In this new model when x =  5 the year is 2005, so the new model is the same as the old except the start year is now 2000.

Bob

I thought 0 = year 2000, 3 = year 2003 and 5 = 2005.

If not, why?

Bob

Administrator

Registered: 2010-06-20

Posts: 10,198

Re: Digital Music Revenues

r(x) = R(x-5) = 170.7(x-5)^2 + 1373(x-5) + 1080

If you put x = 0 that computes R(0-5) = R(-5)

However when you put x = 5 that computes R(5-5) = R(0) which is 1080 the amount for 2005.

If the formula works for years before 2005 then x=0 will compute the revenue for a year 5 years before2005, ie 2000.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

nycguitarguy

Member

Registered: 2024-02-24

Posts: 549

Re: Digital Music Revenues

r(x) = R(x-5) = 170.7(x-5)^2 + 1373(x-5) + 1080

If you put x = 0 that computes R(0-5) = R(-5)

However when you put x = 5 that computes R(5-5) = R(0) which is 1080 the amount for 2005.

If the formula works for years before 2005 then x=0 will compute the revenue for a year 5 years before2005, ie 2000.

Bob

Ok. Thanks. I think it's time to move on.