Calculus
posted by PLEASE HELP! PR on .
At the moment OHaganBooks is selling 1000 books per week and its sales are rising at a rate of 200 books per week. Also, it is now selling all its books for $20 each, but the price is dropping at a rate of $1 per week. I need to know at what rate OHaganBooks' revenue is rising or falling given these conditions. I would also like to see the company's revenue increase at a rate of $5000 per week. At what rate would sales have to have been increasing to accomplish this?
Can somebody help me answer this and explain the steps to solve the problem?
Please help me this project is due tomorrow morning!!

We tried to help you with this several days ago. What did you not understand?

Michael I have a question for you about the simplifying and taking a derivative

i am a different person and i still do not understand it
i get R'=3000400X
but i don't understand wat to do with the 5000 
Ben  I just answered you on your original post "Calc."
"PLEASE HELP!"  Your equation is not correct.
What is the basic formula for calculating revenue? Think about how a bookstore gets money if all its books are priced equally. 
R=p*q

Right. Now how do you implicitly differentiate that?
Follow the product and chains rules. 
Follow the product and chain rules.**

R'=p'(q)+p(q')

All you have to do is read the problem and identify p', q, p, and q'. Plug them in to get your change in rate of revenue (R').

ok i got
p=20
p'=1
q=1000
q'=200
and when i plugged them in i got r'=3000
is that right? 
Yes, don't forget your dollar sign and labeling. (What does the $3000 mean?)
For the second part, plug in R' = 5000 and fill in all your other variables except q'. Then, solve for q'. 
Ok $3000 is the rate at that the revenue is rising.
Ok for the second answer i plugged it in and i got
30=q' 
The company's revenue increases at a rate of $3000 per week. (You need the unit of time.)
Check your algebra for the second part. 
ok i redid it
so q'=300? 
Your number is right, but don't forget your labeling.

Good work Michael, thanks.

So sales must increase at a rate of 300 books per week.
Thank U So much!
im gonna work on the second half of the problem now. 
That's correct. Good job!
(Thanks, bobpursley.)