Problema Solution

The revenue R received for selling x stereos is given by the formula

R=-(x^2/3)+70x-800.

How many stereos must be sold to obtain the maximum revenue?

Find the maximum revenue.

Answer provided by our tutors

The equation is ambiguous, as "(x^2/3)" can be interpreted as either "(x^(2/3))" or "((x^2)/3)".  A parabolic equation should be accepted as "((x^2)/3)". 

Graphing the equation allows one to see how the revenue 'R', maximizes when setting 'x' equal to the maximum value:

R = -((x^2)/3)+70x-800

graph for standard form

R= -(1/3)(x-105)^2 + 2875

So x=105 will maximize the revenue since revenue tails off whenever x>105 or x<105.