Need help solving question

Question

The revenue R received for selling x stereos is given by the formula R=-x^2/5+80x-1000. How many stereos must be sold to obtain the maximum revenue? Find the maximum revenue.

Answer 1

You're asked to find the maximum revenue (y-value) and the number sold (x-value) at the vertex of your parabola.

 

Use the formula x= -b/2a to find the x-value at your vertex, and then plug back into the formula to find the corresponding y-value.

 

 

See my other answer to your question for detailed step-by-step instruction.