HELP(Quadratic Formula) Find the equilibrium price and quantity,given with the Demand function (D) and the supply function (S)

[MarieLentzFiji]

Find the equilibrium price and quantity,given that the Demand Function (D) and the supply fuction (S) is:
D = 1.5q² - 15q + 35
S = 2q+7

 

[Dr.Peterson]

Can you show us what you did, and what went wrong?

Have you been taught what to do when you get two solutions?

 

[MarieLentzFiji]

Can you show us what you did, and what went wrong?

Have you been taught what to do when you get two solutions?

No i haven't been taught what to do when i get to equations, thats why im confused.

 

[HallsofIvy]

Then where did you get this problem? Do you know what "D", "S", and "q" represent? What does "equilibrium" mean?

 

[MarieLentzFiji]

Then where did you get this problem? Do you know what "D", "S", and "q" represent? What does "equilibrium" mean?

For homework, D is the demand and S is the supply i think, im not sure about what equilibrium means

 

[Deleted member 4993]

For homework, D is the demand and S is the supply i think, im not sure about what equilibrium means

Do a google search with key words:

equilibrium price and quantity​

and tell us what you find.

 

[JeffM]

Find the equilibrium price and quantity,given that the Demand Function (D) and the supply fuction (S) is:
D = 1.5q² - 15q + 35
S = 2q+7

This looks odd. Check the problem statement.

 

[HallsofIvy]

You did not say what "q" represents. Usually in problems like this the "demand" and "supply" functions are given as "q= f(p)" and "q= g(p)" where "q" is the quantity that will be supplied at a given price "p" or demanded at a given price "p". It does not make sense to me to have them equal to "P" and "S". Do you mean that "P" and "S" are the prices at which a given amount "q" will be demanded or supplied?
Normally, in order to get people to "demand" more you have to lower price so the "demand" equation should be a decreasing function of q. I suspect that is why JeffM says "that looks strange".

It should make sense to you that the higher the price of a good the less will be "demanded" but the amount that can be "supplied" will be greater- and vice versa. The "equilibrium" will be at that price were the two amounts "demanded" and "supplied" are equal. That is "D= S" so \(\displaystyle 1.5q^2- 15q+ 35= 2q+ 7\) solve that equation for q.