Demand is defined as the amount of goods and services that consumers want and are able to purchase at a given price. The law of demand states that demand decreases as price increases - as prices rise, consumers will buy less of a good. This relationship is depicted through a demand curve, which typically slopes downward to the right. A shift in the demand curve occurs when demand increases or decreases for reasons other than price changes, such as changes in consumer income. The demand function can be used to mathematically represent the relationship between price and quantity demanded. Factors that influence demand include price, income, tastes, population size, expectations about the future, and needs.

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Demand
B y :
A r e l l i a S a n a n t h a 2 1 0 8 0 5 7 4 0 7 7
N a u f a l A c h m a d 2 1 0 8 0 5 7 4 0 7 8
F e r d i n a n Ti t u s 2 1 0 8 0 5 7 4 0 8 7
Ya s i n t a R a c h m i 2 1 0 8 0 5 7 4 1 4 3

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What is Demand ?
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Definition of Demand
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Demand (permintaan) is a term for the amount
of goods and services that are desired and needed to
be purchased at a certain price level and time
according to the market.

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What is Law of Demand ?
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Law of Demand (Hukum Permintaan) is a
fundamental principle of economics that states that at
higher price consumers will demand a lower quantity of
good.
Shortly, Law of Demand said “when the price
goes up, the demand from consumer will be lower. And
if the price goes down, the demand from customer will
be high.”

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Demand Curve (Kurva Permintaan)
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It can be seen from
this curve. That, when
the price goes up, the
lower the level of
demand from
consumers.

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Shifting in Demand Curve
(Pergeseran Kurva Permintaan)
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The change in the curve is called a curve shift,
which is a condition when the demand curve shifts to the
left or to the right. Usually it is due tochanges in income
from the customers.
This change in the curve is called a curve shift,
which is a condition when the demand curve shifts to the
left or to the right

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It can be seen from this curve, that when consumers experience an increase
in income, the curve will move to the right. That means, even though the price of
goods increases, the quantity demanded will remain or even increase.
Otherwise, when consumers experience a decrease in income, the curve will move
to the left. That means, even if the price does not change, the quantity will continue to fall.
Moreover, if the price increases, the quantity demanded will decrease drastically.

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Example
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Shop A sells item X for Rp 5.000,00 per unit. Then,
because there is an price increase in materials that they use, the
price of item X increases to Rp 10.000,00 per unit. Of course, this
will have an impact on the level of demand from their customers. It
can be presented as a table like this
Price Quantity
5.000 30
10.000 25
15.000 20
20.000 15
25.000 10
From this table, Can be concluded that the higher the price (P),
the lower the demand (Q). This applies not only in this store, but also in
other stores, even in a large market.

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Demand Function (Fungsi Permintaan)
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Demand function form is P=a-bQ, or Q=a-bP.
To calculate and determine the demand function, use the formula
𝐏−𝐏𝟏=𝐐−𝐐𝟏
𝑷𝟐−𝑷𝟏=𝑸𝟐−𝑸𝟏
P : price of goods per unit
Q : quantity of goods demanded
a : constant number
b : slope/gradient
P : price
P1 : starting price
P2 : final price
Q : demand
Q1 : starting demand
Q2 : final demand

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Example
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If the price of an item is Rp 60,00 per unit, then
the quantity of demand is 20 units. And if the price is Rp
40,00 per unit, the quantity of demand is 30 units. So to find
the equation of the demand function we use the formula
before. So it will become like this.
𝐏 − 𝐏𝟏 = 𝐐 − 𝐐𝟏
𝑷𝟐 − 𝑷𝟏 = 𝑸𝟐 − 𝑸𝟏
𝐏 − 𝟔𝟎 = 𝐐 − 𝟐𝟎
𝟒𝟎 − 𝟔𝟎 = 𝟑𝟎 − 𝟐𝟎
𝐏 − 𝟔𝟎 = 𝐐 − 𝟐𝟎
−𝟐𝟎 = 𝟏𝟎
𝟏𝟎𝐏 − 𝟔𝟎𝟎 = −𝟐𝟎𝐐 + 𝟒𝟎𝟎
𝟏𝟎𝐏 = −𝟐𝟎𝐐 + 𝟒𝟎𝟎 + 𝟔𝟎𝟎
𝟏𝟎𝐏 = −𝟐𝟎𝐐 + 𝟏𝟎𝟎𝟎
𝐏 = −𝟐𝟎𝐐 + 𝟏𝟎𝟎
or
𝐏 = 𝟏𝟎𝟎 − 𝟐𝟎𝐐
After calculating with the formula, it can be known that the demand function is P = 100 - 20Q.

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Factors that Affecting Demand
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1. Price of the goods and services
2. Consumer’s income
3. Consumer’s taste
4. Number of consumer
5. Consumer prediction about conditions in the future
6. Intensity of consumer needs

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