# Thread: rate of change problems

1. ## rate of change problems

Hello everyone,

I desperately need help with this assignment. I am a international student and it's my first time ever being taught calculus and in another language than I'm used to. I really hope someone could help, as I need it for an assignment for monday.

The assignment is attached below

Rate of change problems.pdf
Thanks in advance :)

2. ## Re: rate of change problems

What work have you done? The instructions seem pretty straightforward. I am not sure what additional insight I could shed on the problems without knowing where you are struggling.

3. ## Re: rate of change problems

I pretty much don't understand any of it tbh. The school in Denmark where i come from have not taught me anything like this what so ever and i've had very short time to learn it (I've only had 4 weeks of school in a 9 week program due to the recent college strike in Ontario). So i was kind of hoping some one would be so kind to make it for me. As I have just joined this forum, I am not aware if that is allowed but I hope it is.

4. ## Re: rate of change problems

Part 1(a) is looking to see if you understand composition of functions. This link should shed some light on the subject. While it would be easy enough for me to just give you the answers, it seems like it would be more beneficial for you to actually learn the material. So, let's start here. Can you do 1(a) after reading this article?
https://www.mathsisfun.com/sets/func...mposition.html

If not, where are you struggling?

5. ## Re: rate of change problems

I actually had a tutor help me with the first part of the assignment and this is the answer that he gave me. So what I'm really asking for is help with part 2. :)

6. ## Re: rate of change problems

... this is the answer that he gave me.

so, what does this expression represent? do you understand where it came from?

7. ## Re: rate of change problems

Also, that is not the answer to 1 a). It is the answer to another part of the problem, but not 1 a.

8. ## Re: rate of change problems

This forum and others like it avoid giving answers. We give help so that you can answer questions on your own during your exam WHEN WE WON'T BE THERE TO HELP YOU.

Question 1a is about the revenue function. You are given a general definition. What is it?

Do you understand why that general definition makes sense?

In the specific problem given, what revenue function do you get when you apply the general definitions?

By the way, what is the name of the course you are taking?

9. ## Re: rate of change problems

"Revenue", the amount of money brought in by selling "x" items at price "p" per item is px. Here you are told that $p= \frac{750}{\sqrt{x}}- 2$ so the revenue is $x\left(\frac{750}{\sqrt{x}}- 2\right)= \frac{750x}{\sqrt{x}}- 2x= 750\sqrt{x}- 2x$. That can also be written as $750x^{1/2}- 2x$ NOT the $750x^{-1/2}- 2x$ that you give. Perhaps you copied it incorrectly.

The "marginal revenue" is the additional revenue you get by selling "one more". If you sell x items, the revenue is $750x^{1/2}- 2x$. If you sell "one more", x+ 1, the revenue is $750(x+ 1)^{1/2}- 2(x+ 1)$. How much more is the second than the first?

To find the "marginal revenue when 100 floor lamps are sold", calculate the revenue when x= 100, then calculate the revenue when x= 101, and subtract.

10. ## Re: rate of change problems

I think i've got it.

The answer i gave is the answer to part b.

The answer to part a is

and the answer to part c is

11. ## Re: rate of change problems

Originally Posted by JeffM
This forum and others like it avoid giving answers. We give help so that you can answer questions on your own during your exam WHEN WE WON'T BE THERE TO HELP YOU.

Question 1a is about the revenue function. You are given a general definition. What is it?

Do you understand why that general definition makes sense?

In the specific problem given, what revenue function do you get when you apply the general definitions?

By the way, what is the name of the course you are taking?
The program i'm taking is called international business

12. ## Re: rate of change problems

Originally Posted by jonasvillum99
I think i've got it.

The answer i gave is the answer to part b.

The answer to part a is

and the answer to part c is
This is correct. Do you have any questions about how one arrives at that answer?

13. ## Re: rate of change problems

No i think i got it.

I do have a question whether or not i made the second part correct tho.

This is what i have so far, it is both a, b and c

14. ## Re: rate of change problems

Originally Posted by jonasvillum99
No i think i got it.

I do have a question whether or not i made the second part correct tho.

This is what i have so far, it is both a, b and c
That is correct

15. ## Re: rate of change problems

Thank you very much with the help