Market demand, profit function, and output?

[Quixotic]

If I know market demand is p= 40-.05y and the profit function of a representative firm is
R(p)=p^2 -2p -250

what is the y(p) and the long-run equilibrium y* and number of firms in the market, j*?

I don't understand the difference between y(p) and the y* or how to find these values. Any instruction hugely appreciated. I originally got the answer y= 800- p/.05 but the instructor said this is demand, not supply. What do I do to get the y(p) and y* and this number of firms thing?

 

[stapel]

If I know market demand is p= 40-.05y and the profit function of a representative firm is R(p)=p^2 -2p -250, what is the y(p) and the long-run equilibrium y* and number of firms in the market, j*?

I don't understand the difference between y(p) and the y* or how to find these values. Any instruction hugely appreciated. I originally got the answer y= 800- p/.05 but the instructor said this is demand, not supply. What do I do to get the y(p) and y* and this number of firms thing?

How does your book define "y(p)", y*, and j*, particularly in relation to p, y, and R? What are the exact definitions? Thank you!

 

[Quixotic]

How does your book define "y(p)", y*, and j*, particularly in relation to p, y, and R? What are the exact definitions? Thank you!

Unfortunately we aren't using a textbook, this is a review of the pre-requisite material before the semester starts at the end of August! We were referred to Varian's Intermediate Microeconomics, from which I gather p should be the price of an individual good, j* is the number of firms in the market, y* is the number of output goods in the market, and p* is the market price. The firms are identical and face identical input prices.

I'm sure there is something little I'm missing with this, but I'm quite confused and frustrated.

 

[stapel]

..this is a review of the pre-requisite material before the semester starts....

So this is stuff that was covered in the previous class at the end of the previous school year? Okay, what did that book (or that instructor) give as the definitions? Thank you!

 

[Quixotic]

So this is stuff that was covered in the previous class at the end of the previous school year? Okay, what did that book (or that instructor) give as the definitions? Thank you!

Ah, I just got admitted to a business program when I have a philosophy undergraduate degree. Seriously, I'm lost. The only instructions in the e-mail and the reference book are the ones I listed above.

 

[stapel]

Ah, I just got admitted to a business program when I have a philosophy undergraduate degree. Seriously, I'm lost. The only instructions in the e-mail and the reference book are the ones I listed above.

So you've never studied this material before?

If so then, because this is prerequisite material (that is, because it is REQUIRED for the upcoming courses), you should immediately talk with your academic advisor. You have been placed in the wrong course, and need to be tested to find the correct placement. Math is incremental, and you simply can't do the new material without having first learned the prerequisite material.

Somebody (surely mistakenly) has set you up to fail, and that isn't fair. Your advisor should be able to fix this for you. Good luck!