Answer:
The demand equation is: D=-4p+23
Step-by-step explanation:
To get started, we should keep in mind that the market price (p=3) occurs when supply equals demand ,therefore when p=3
S=2(3)+5=11
Thus, when p=3 D=11 and, according to the problem when p=1 D=19.
We already know two points on the demand curve. Great!
The demand equation is linear, so it has form D=bp+c.
The variable b is the slope of the demand linear equation . It can be computed through the formula
. equation 1
Substituting the two points (3,11) and (1,19) on equation 1.
b=-4
Now we can find the value of intercept of the demand equation c trough point-slope form y-y1=b(x-x1).
We can use any of the points. Let's take (3,11) and write in point-slope :
y-11=-4(x-3)
y=-4x+11+12
y=-4x+23
Rewrite the linear equation according our variables D and p
D=-4P+23
Finally we found the demand equation !