Assumptions: perfect competition
(ko đc cộng price)
50
35
20
+
price rise -> quantity demand fall
price fall -> quantity demand rise
price tăng -> mn đổ xô đi mua gold, stock, real estate
P
y=f(x)
Qd = f(Px; Py; I; T; E; N;..)
Px: the price of this good
Py: the price of related good
I: income of buyers
E: Expectation of buyers
T: taste of buyers
N: number of buyers
a P = Qd -b
P = Qd -b /a
-> inverse demand function
Qd = aP+b (a<0)
50 = a*10+b
35 = a*20+b
Then a =-1.5 (<0)
and b = 65
Demand function is Qd = -1.5P + 65
P=-2/3Qd + 130/3
= change in quantity demanded only (not change in D)
Caused by the change in Px
-> movement along the D curve
= change in D
caused by Py; I, T, E, N
Example: weather becomes hotter
-> Qd increase at each price
-> D increase
-> D curve shift to the right
P substitute rise -> D increase
P subtitute decrease -> D decrease
P pepsi rise -> Qd pepsi decrease
-> Qd coke increase at each price
-> D coke rise -> D coke shift to the right
P complement increase -> D decrease
P comliment decrease -> D increase
Price printer increase -> Qd printer decrease
-> Qd ink giảm at each P -> D ink giảm
->D ink shift to the left
I tăng -> D tăng
I giảm -> D giảm
I tăng -> D giảm
I giảm -> D tăng
I
Engel curve cho biết mối quan hệ thế nào giữa price và quantity demanded
A. positive
B. negative
C. both
D. none. -> D is correct
Vì engel curve show mối qh giữa income và quantity demande
Engel curve
inferior good
I
normal good
0
Q
N tăng -> D tăng
N giảm -> D giảm
15
35
55
Qs = aP+b
15 = a*10+b
35 = a*20+b
Then a=2 (>0)
and b=5
Supply function is Qs = 2P-5
P i tăng -> Qs giảm at each price
-> S giảm -> S curve shift to the left
P
Tax tăng.
S2.
S1
Subsidy tăng
P
<—
0
S2.
S1
P1
—>
Q
0
S1
P
Q
0
Q1
Q