Recall that in​ business, a demand function expresses the quantity of a commodity demanded as a function of the​ commodity's unit price. A supply function expresses the quantity of a commodity supplied as a function of the​ commodity's unit price. When the quantity produced and supplied is equal to the quantity​ demanded, then we have what is called market equilibrium.

The demand function for a certain compact disc is given by the function p=-0.01x^2-0.6x+10 and the corresponding supply function is given by p=-0.01x^2-0.2x+4, where p is in dollars and x is in thousand of units.

Find the equilibrium quantity and the corresponding price by solving the system consisting of the two given equations.

1 answer

To find the equilibrium point, we need to equate the quantity demanded and the quantity supplied. This would mean setting the two equations equal to each other and solving for x:

-0.01x^2-0.6x+10 = -0.01x^2-0.2x+4

First, we can simplify by cancelling similar terms on both sides of the equation. The -0.01x^2 terms cancel out so we are left with:

-0.6x+10 = -0.2x+4

Next, we can rearrange the equation to isolate the variable:

-0.4x = -6

Finally, we can solve for x by dividing both sides of the equation by -0.4, thus getting our equilibrium quantity (x):

x = 15 (in thousands of units)

Now we can substitute x = 15 into either the demand or supply function to find the equilibrium price (p). Let's substitute it into the demand function:

p=-0.01(15)^2-0.6(15)+10
p=-0.01(225)-9+10
p=-2.25-9+10
p=-1.25+10
p=8.75

Therefore, the equilibrium quantity is 15,000 units and the equilibrium price is $8.75 per unit.