# What's wrong with my algebraic expression?

Mentor note: moved to homework forum

A store has been selling 200 DVD burners a week at $350 each. A market survey indicates that for each$10 rebate offered to buyers, the number of units sold will increase by 20 a week. Find the demand function and the revenue function. How large a rebate should the store offer to maximize its revenue?

my expression: R(x) = ($350-$10x)(200+20x)

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## Answers and Replies

Mark44
Mentor
A store has been selling 200 DVD burners a week at $350 each. A market survey indicates that for each$10 rebate offered to buyers, the number of units sold will increase by 20 a week. Find the demand function and the revenue function. How large a rebate should the store offer to maximize its revenue?

my expression: R(x) = ($350-$10x)(200+20x)
What did you get for the demand function?

What did you get for the demand function?
according to my textbook, demand function is also the price function... so i think that should be the ($350-$10x) part of the expression...?

Mark44
Mentor
according to my textbook, demand function is also the price function...
I think you might be misinterpreting what the book is saying. Price and demand are two different things. Usually the demand is written as a function of the price, p.

According to your first post, when p = 350, the demand d will be 200. And when the price is decreased by $10, the demand is forecast to be 220. Assuming that demand is a linear function of price, you should be able to write the demand function from that information. Terrell said: so i think that should be the ($350-$10x) part of the expression...? Ray Vickson Science Advisor Homework Helper Dearly Missed Mentor note: moved to homework forum A store has been selling 200 DVD burners a week at$350 each. A market survey indicates that for each $10 rebate offered to buyers, the number of units sold will increase by 20 a week. Find the demand function and the revenue function. How large a rebate should the store offer to maximize its revenue? my expression: R(x) = ($350-\$10x)(200+20x)

Why do you think your expression is wrong? Aside from failing to define what you mean by 'x', it looks OK to me, provided that you are extra careful about what 'x' actually means.

Now: what about the rest of the problem?

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