9 Ilie Babaita

Analele Universitii Constantin Brncui din Trgu Jiu, Seria Economie, Nr. 2/2010

Annals of the Constantin Brncui University of Trgu Jiu, Economy Series, Issue 2/2010

91

TEORIA CONSUMATORULUI

Prof. univ. dr. Ilie BBI Universitatea de Vest Timioara

Rezumat

In viziunea agentului economic consumatorul prezinta un tip de comportament raional, ce are ca scop maximizarea satisfaciei obinut prin utilizarea de mrfuri. Pentru a determina acest comportament raional, pornim de la premisa c fiecare consumator are informaii exacte i complete privind: structura de mrfuri existente pe pia i capacitatea acestora de a raspunde anumitor dorinte ale acestuia, nivelul preului de pia i mrimea venitului sau care poate fi alocat ntr-o perioad dat, pentru a achiziiona diferite produse. n scopul de a satisface nevoile sale, consumatorul actioneza raional alegand un co de bunuri care sa furnizeze cea mai mare satisfacie in conditiile unui venit realizat si a pretului ce trebuie achitat pentru un bun economic. Cuvinte cheie: consum,utilitate,utilitate marginala

1. Definirea Consumatorilor

Consumatorul este un agent economic, cruia i este caracteristic achiziionarea i consumul de bunuri, pornind de la un venit disponibil dat. El ntreine relaii cu ali ageni economici prin intermediul unor diverse operaiuni. Astfel, consumatorul este legat de ntreprinderi prin munca pe care o presteaz i remuneraiile ce decurg din aceasta, dar i prin intermediul cumprrii de produse i al preurilor pe care el accept s le plteasc n schimbul acestora.

Dispunnd de un venit limitat, consumatorul este constrns s decid n privina utilizrii ct mai raionale a acestuia, definind judicios structura cheltuielilor sale.

Consumatorul poate fi o persoan fizic sau o comunitate (de exemplu, o familie), caz n care avem n vedere veniturile

CONSUMER THEORY

Prof. PhD Ilie BBI West University of Timisoara

Abstract The behaviour of the economic agent customer is a rational type of behaviour in order to maximize the satisfaction achieved through the use of commodities. In order to determine a rational behaviour, we start from the premise that every costumer has complete and accurate information on: the structure of commodities existing on the market and their ability to comply with certain wishes, market prices levels and the size of income that shall be spent in a given period in order to purchase various commodities. In order to fulfil its needs, the rational costumer has to chose from a basket of commodities the ones that: provide the greatest satisfaction under the circumstances of income and price restrictions. Keywords: consumption, utility, marginal utility

1. Consumer Definition

The consumer is a trader, who is characteristic acquisition and consumption of goods, from a given disposable income. He maintains relationships with other operators through various operations. Thus, the consumer is related businesses that provide labor and remuneration therefrom, but also through the purchase of products and prices that he agrees to pay in exchange. With a limited income, the consumer is constrained decide on its rational use as defining its judicious expenditure pattern.

The consumer can be an individual or a community (eg a family), in which case we consider the overall revenue and expenditure. To simplify the analysis



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i cheltuielile globale. Pentru a simplifica analiza, n cele ce urmeaz vom raiona avnd n vedere ntotdeauna o persoan fizic.

Consumatorul i utilizeaz venitul pentru a cumpra unele bunuri i a obine prin consumul acestora o anumit satisfacie. Problema care se ridic privete ns alegerea cantitilor ce se cumpr din diferitele bunuri ce se ofer pe pia, n funcie de gusturi, preferine i bugetul disponibil.

Dintre nevoile pe care le poate avea un consumator, analiza microeconomic este interesat doar de nevoile economice, adic de nevoile care pot fi satisfcute printr-o operaiune economic. Astfel, a cltori n timp nu este o nevoie economic, deoarece o asemenea nevoie nu poate fi satisfcut prin nici o operaiune economic la ora actual. Dimpotriv, a bea un suc de mere este o nevoie economic, deoarece aceast nevoie poate fi oricnd satisfcut prin cumprarea de pe pia i consumul acestui suc.

Nevoile economice pot fi satisfcute prin consumul unor bunuri economice. Aceste bunuri pot fi definite n dou modaliti diferite:

1) Un bun este economic, dac poate fi obiectul unei tranzacii, adic a unei operaiuni de vnzare-cumprare. Conform acestei definiii, bunurile economice sunt mrfuri. Exist ns i bunuri libere, disponibile n cantiti nelimitate i achiziionabile la un pre nul, dei satisfacia pe care consumul lor o poate procura consumatorului nu este de loc neglijabil (de exemplu: apa mrii, aerul, nisipul de pe plaj etc.)

2) Bunurile economice sunt acele bunuri, care pot face obiectul unei producii de serie, adic bunurile care pot fi reproduse oricnd. Dac reinem aceast definiie, excludem ansamblul bunurilor nereproductibile, cum ar fi, de exemplu, operele de art, vinurile vechi, dei satisfacia pe care o procur posesorilor lor este deosebit de mare.

below we always argue with regard to an individual.

Consumers use their income to buy

some supplies and get them by eating a certain satisfaction. The question concerns choice but to buy quantities of various goods that are offered on the market, depending on tastes, preferences and budget available.

Among the needs they may have a

consumer is interested only microeconomic analysis of economic needs, ie needs can be met by an economic transaction. Thus, travel time is an economic need, such as the need may be satisfied by any economic transaction today. Conversely, drinking aplle juice is an economic need, because this need can always be satisfied by market purchase and consumption of this juice. The economic needs can be met by the consumption of economic goods. These assets can be defined in two different ways: 1) A good is economic, it can be a settlement, ie a sale transaction. Under this definition, economic goods are goods. There are also free goods available in unlimited quantities and purchased at a price zero, although their consumption satisfaction a consumer can buy is not at all negligible (eg sea water, air, beach sand, etc.). 2) Economic goods are those goods that may be subject to mass production, ie those that can be reproduced at any time. If you remember the definition exclude all nereproductibile goods, such as, for example, art works, old wines, although satisfaction that their proxy holders are particularly high. 2. Consumer Area A consumer who must decide what quantities of each item you consume, you



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2. Suprafaa de consum

Un consumator care trebuie s decid ce cantiti va consuma din fiecare bun, trebuie s aleag din ansamblul opiunilor posibile un anumit co de consum. Presupunnd c exist pe pia n bunuri de consum, diferitele couri de consum posibile vor avea forma : ( )iniii xxxB ,...,, 21= unde ( )njxij ....,,2,1= reprezint cantitatea din bunul j coninut n coul de consum i.

Numrul courilor de consum posibile este infinit. Ansamblul acestor couri formeaz suprafaa de consum. Teoria microeconomic pornete de la ipoteza c acest ansamblu este nelimitat, cuprinznd toate courile compuse din cantiti pozitive sau nule ale celor n bunuri de pe pia (cantitile negative nu au sens n cadrul acestei analize). Deoarece ns piaa nu poate oferi cantiti nelimitate de bunuri, teoretic trebuie s avem n vedere o limit superioar a disponibilitilor de bunuri de consum. De asemenea, este logic s avem n vedere i un consum minimal, care poate asigura minimul vital al consumatorului.

A

B

20

25

ymin = 75

2 xmin = 5 X

Yymax

xmax

Fig. 1.1. - Suprafaa de consum

Pentru a simplifica analiza, este util s reducem diversitatea ansamblului de couri disponibile i s avem n vedere o economie n care piaa ofer doar dou bunuri (x i y). n acest caz, suprafaa de consum se poate reprezenta ca n Figura 1.1.

must choose from all possible choices a consumer cart. Assuming that the market is not consumer goods, different consumption baskets as possible will be: ( )iniii xxxB ,...,, 21= where ( )njxij ....,,2,1= j is the amount of property contained in the consumer cart i. Possible number of consumer cart is infinite. Together, these form the area of consumer cart. Microeconomic theory assumes that this set is infinite, consisting of cart containing all positive or zero quantity of the goods in the market (Negative quantities do not make sense in this analysis). But because the market can not provide unlimited quantities of goods, theoretically we should have an upper limit to the availability of consumer goods. It is also logical to consider a minimum consumption, which can provide vital minimum consumer.

A

B

20

25

ymin = 75

2 xmin = 5 X

Yymax

xmax

Fig. 1.1. - Suprafaa de consum

To simplify the analysis, it is useful to reduce the overall diversity of carts available and to consider the market economy offers only two goods (X and Y). In this case, the area consumption can be as shown in Figure 1.1. In the case of two goods, consumption baskets all face is the same as X-Y and



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n cazul a dou bunuri, ansamblul courilor de consum se confund cu cadranul x-y, iar suprafaa de consum este zona haurat. Limita disponibilului din cele dou bunuri este xmax , respectiv ymax , iar minimul vital este xmin, respectiv ymin. Coul A(20x, 25y) aparine suprafeei de consum, dar coul B(5x, 5y) nu.

3. Relaia de preferin i de indiferen a consumatorului

Pentru a determina cantitile pe care le va cumpra, consumatorul trebuie s ierarhizeze toate courile din suprafaa de consum n funcie de preferinele sale. Pentru a traduce formal acest clasament, se definete relaia de preferin i de indiferen, astfel: 9 Relaia de preferin strict permite s se compare dou couri de bunuri i s se determine coul preferat fa de cellalt: A > B, adic coul A este strict preferat fa de coul B. 9 Relaia de indiferen stabilete c dou couri de consum aduc exact aceeai satisfacie consumatorului, deci acesta este indiferent fa de cele dou couri: A B, adic coul A este indiferent fa de coul B. 9 Relaia de preferin combin cele dou relaii de mai sus: AB, adic coul A este preferat sau indiferent fa de coul B sau coul A este cel puin la fel de preferat ca i coul B. Aceast relaie permite consumatorului s clasifice ansamblul courilor posibile.

Fiecare agent posed o structur a preferinelor specific numai lui, dar relaia de preferin trebuie s verifice cteva ipoteze (axiome) pentru ca un consumator s fie raional. a) Axioma de totalitate: consumatorul trebuie s fie capabil s compare un co cu toate courile posibile din suprafaa de consum, adic nu exist couri neclasificabile n suprafaa de consum. Ca urmare, consumatorul poate afirma c este verificat ntotdeauna una din urmtoarele situaii: A

consumption area is shaded area. Limited availabilities of the two goods is Xmax respectively Ymax and the minimum is vital xmin, ymin respectively. Cart A (20x, 25y) belongs to the consumer area, but Mark B (5X, 5Y) no. 3. Relationship of consumer preference and indifference To determine the quantities they buy, consumers should prioritize all of the area of consumer baskets based on their preferences. To translate this formal classification, defines the relationship of preference and indifference, as follows: 9 strict preference relation allows to compare two cart of goods and to determine preferred to other cart: A> B, A cart that is strictly preferred to Mark B 9 indifference relationship states that two consumer carts without the exact same consumer satisfaction, so he is indifferent to the two spots: A = B, or "cart A is indifferent to B . 9 Relationship preferably combine the two above relations: A B, which means "cart A is preferred or indifferent to cart B" or "cart A is at least as preferred as cart B". This relationship allows consumers to rank all possible carts. Each agent has a specific structure but his preferences, but preferably relationship must verify some assumptions (axioms) to the consumer is rational. a) the axiom of all: the consumer must be able to compare a basket of all possible spots in the area of consumption, ie no surface not covered consumer cart. As a result, consumers may say that is always checked one of the following situations: A B or B A. b) axiom of reflexivity: each cart is indifferent to himself, so we can write: A A (this axiom has only a mathematical interest).



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B sau B A. b) Axioma de reflexivitate: fiecare co este indiferent fa de el nsui, deci se poate scrie: A A (aceast axiom are doar un interes matematic). c) Axioma de tranzitivitate: dac A B i B C, atunci i A C.

Dac unui consumator i se propun dou couri de bunuri dintre toate cele posibile, l va alege pe cel care va corespunde cel mai bine preferinelor sale. Atunci cnd se consum un bun, se obine un beneficiu sau o satisfacie. Economitii numesc acest beneficiu sau aceast satisfacie utilitate i consider c atunci cnd consumatorul alege ntre diverse bunuri, el ncearc s obin cea mai mare utilitate n raport cu venitul su. 4. Teoria utilitii

Trebuie s deosebim utilitatea total de cea marginal. Utilitatea total (U) a unui bun x msoar satisfacia global pe care o resimte consumatorul n urma consumrii ntregii cantiti achiziionate din bunul dat. Nivelul utilitii totale depinde de cantitatea consumat din bunul x, deci U = U(x).

Utilitatea marginal a bunului x, (MUx) reprezint suplimentul de utilitate provocat prin consumul unei uniti adiionale din acest bun (ceteris paribus). Cu alte cuvinte, utilitatea marginal msoar variaia utilitii totale (U) determinat de consumarea unei uniti adiionale din bunul dat (dac bunul x este imperfect divizibil), respectiv variaia utilitii totale n raport cu o variaie infinit de mic (x 0) a cantitii consumate (dac bunul este perfect divizibil). Formal, acest lucru se poate scrie astfel: ( )[ ]

xyxUyxxU

xyxUMU X

+== ),(,),(

respectiv: ( ) ( )xUdxdU

xyxUMU

xX'

0

,lim === ,

adic prima derivat a funciei de utilitate. Cu ajutorul utilitii marginale putem

determina cum evolueaz nivelul de

c) The axiom of transitivity: if A B and B C, then A C. If a consumer is proposing two cart of goods of all possible, we will choose one that best fits his preferences. When a good is consumed, to obtain a benefit or satisfaction. Economists call this benefit or that benefit satisfaction and believes that when consumers choose between different goods, he seeks the largest utility in relation to its income. 4. Utility theory Must distinguish the total marginal utility. Total utility (U) has a good X measured overall satisfaction that a consumer feels after consuming the entire amount of the asset acquired since. Total utility level depends on the quantity consumed of good x, so U = U (x). Marginal utility of good x (MUX) is caused by eating supplement utility of additional units of this good (ceteris paribus). In other words, the marginal utility measured changes in total utility (U) due to consumption of additional units of the given object (if object x is imperfectly divisible) and total utility changes compared with an infinitely small change (Dx 0) quantity consumed (if the property is perfectly divisible). Formally, this can be written as: ( )[ ]

xyxUyxxU

xyxUMU X

+== ),(,),(

respectively: ( ) ( )xUdxdU

xyxUMU

xX'

0

,lim ===

ie the first derivative of utility function. Using marginal utility can determine how evolving consumer satisfaction when consuming an increasing amount of good x. Depend on the need for consumer



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satisfacie al consumatorului cnd consum o cantitate cresctoare din bunul x. Satisfacia depinde de intensitatea nevoii consumatorului: plcerea este proporional cu lipsa resimit nainte de consumare. Deoarece intensitatea unei nevoi descrete pe msur ce cantitatea consumat sporete, rezult c exist un principiu, o lege a utilitii marginale descresctoare, conform creia dac intensitatea nevoii scade odat cu cantitatea consumat, satisfacia obinut pentru fiecare unitate suplimentar consumat este tot mai puin important dect pentru unitatea consumat anterior.

Umax

5

1 2 3 4 50

2

4

6

8

10U(x)

MUX

U(x)

X 1 2 3 4 50 X

MUX4321

MUX

Fig. 1.10. - Evoluia UX i MUX n raport cu modificarea consumului bunului X

Aceast lege a fost formulat n 1854 de Gossen, care a artat c primul pahar de ap consumat de un cltor din deert i procur acestuia o utilitate imens, al doilea pahar i va aduce un spor de utilitate mai mic .a.m.d.

Ca urmare, dei mrind cantitatea consumat utilitatea total continu s creasc (chiar dac tot mai lent), utilitatea marginal descrete continuu (Fig. 1.10.).

Cnd utilitatea marginal devine nul, utilitatea total va fi maxim, deoarece continund s mrim consumul, utilitatea total nu mai crete, dimpotriv, poate descrete, deoarece dincolo de punctul de saturaie al consumatorului utilitatea marginal a bunului x devine negativ, n sensul c satisfacia se transform n insatisfacie (Fig. 1.11.)

Un consumator raional i sisteaz consumul dintr-un bun n momentul n care a

satisfaction: the pleasure felt is proportional to the lack of prior to consumption. Since the intensity of needs decrease as quantity consumed increases, that is a principle a law of decreasing marginal utility, that if the intensity decreases with the amount consumed need satisfaction obtained for each additional unit consumed is less important than unit consumed above.

Umax

5

1 2 3 4 50

2

4

6

8

10U(x)

MUX

U(x)

X 1 2 3 4 50 X

MUX4321

MUX

Fig. 1.10. - Evoluia UX i MUX n raport cu modificarea consumului bunului X

This law was formulated in 1854 by Gossen, which showed that first glass of water consumed by a passenger in his desert his attorney a huge utility, the second cup will bring lower utility gain etc. As a result, although increasing the total amount consumed usefulness continues to grow (albeit more slowly), the marginal utility decreases continuously (Fig. 1.10.). When marginal utility is zero, total utility will be maximum, because continuing to expand consumption, not increase total utility, by contrast, may decrease because of saturation point beyond the consumer's marginal utility of good x becomes negative, meaning that satisfaction is turns into dissatisfaction (Fig. 1.11.) A rational consumer cease their consumption of a good when it has reached



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atins limita sa de saturaie, adic atunci cnd ultima unitate consumat nu i-a mai adus nici un spor de utilitate. Cu alte cuvinte, cnd utilitatea marginal a unui bun devine egal cu zero, utilitatea total a consumatorului este maxim.

4

4

1

1

U(X)maxU(X)U(X)

MUX

MUX = 0

MUX

Fig. 1.11. - Maximizarea utilitViitotale

Deoarece utilitatea nu poate fi

msurat direct, o msurare indirect se poate realiza, de exemplu, cu ajutorul dispoziiei consumatorului de a plti pentru un anumit bun. Astfel, dac Ion prefer ngheata de vanilie celei de ciocolat, n mod cert este dispus s plteasc mai mult pentru un cornet cu vanilie dect pentru unul cu ciocolat.

Bineneles, preul pe care Ion este dispus s-l plteasc pentru o ngheat de vanilie nu este identic cu preul la care va cumpra cornetul. Acesta din urm depinde nu de preferinele sale, ci de condiiile de pia.

Dispoziia de a plti este un instrument bun pentru msurarea utilitii i ne permite s tim cum i aloc un individ bugetul de-a

its saturation limit, ie when the last unit consumed takes not bring any utility gain. In other words, the marginal utility of an object is zero, total consumer utility is maximum.

4

4

1

1

U(X)maxU(X)U(X)

MUX

MUX = 0

MUX

Fig. 1.11. - Maximizarea utilitViitotale

Since utility can not be measured directly, an indirect measurement can be achieved, for example, with provision for the consumer to pay a certain good. Thus, if John prefers the chocolate and vanilla ice cream, of course is willing to pay more for a cornet with vanilla than chocolate one. Of course, the price that John is willing to pay for not vanilla ice cream is the same price will buy cornet. The latter depends not on its preferences, but market conditions. Available to pay is a good tool for measuring the utility and allows us to know how an individual allocates its budget across its budgetary restraint. If



98

lungul restriciei sale bugetare. Dac msurm utilitatea prin dispoziia de a plti, este posibil s construim un grafic ca n figura 1.12.

S urmrim consumul de ciocolat al unui individ de-a lungul unei zile. Cum evolueaz disponibilitatea marginal a consumatorului de a plti pentru cele 5 batoane de ciocolat? Deoarece satisfacia lui scade pe msur ce crete cantitatea consumat anterior, el va fi dispus s plteasc tot mai puin pentru un baton suplimentar, aa cum se poate vedea n figura 1.12.

Deci, pe msur ce cantitatea consumat crete, satisfacia crete, dar cu o rat descresctoare, pn cnd creterea nceteaz complet (al 5 lea baton are utilitatea marginal nul).

Pentru primul baton care i aduce cel mai ridicat nivel de utilitate marginal, consumatorul este dispus s plteasc 80 u.m., pentru al doilea 60 u.m., pentru al treilea 40 u.m., pentru al patrulea 20 u.m., i n fine, pentru al cincilea, care nu i mai aduce nici un spor de utilitate, nu este dispus s mai plteasc nimic. Din exemplul de mai sus rezult c evoluia dispoziiei marginale a consumatorului de a plti pentru un bun oarecare X, reflect evoluia utilitii marginale a bunului X i, n acelai timp, i evoluia cererii bunului respectiv (DDx). Deoarece utilitatea marginal este descresctoare, descrete i dispoziia de a plti a consumatorului, deci curba cererii sale are panta descresctoare (negativ). Pn cnd utilitatea marginal (MUx) rmne pozitiv, utilitatea total crete; cnd MUx devine nul, utilitatea total este maxim

you measure by the utility to pay, it is possible to build a graph as in Figure 1.12. To track an individual's consumption of chocolate throughout the day. How changing availability marginal consumer to pay for the five bars of chocolate? Since his satisfaction decreases as you increase the amount previously consumed, it will be increasingly less willing to pay for an extra bar, as can be seen in Figure 1.12. So, as the quantity consumed increases, satisfaction increases, but with a decreasing rate until growth ceases completely (the 5 - th bar has zero marginal utility). For the first bar that brings the highest level of marginal utility, consumer is willing to pay 80 mu to 60 mu second for the third 40 um to 20 um, fourth, and finally for the fifth, which May it bring any increase utility is not willing to pay anything in May. The above example shows that the evolution of marginal provision for a consumer to pay some good X, reflecting the evolution of marginal utility of good X, while and demand trends that property (DDx). Since marginal utility is decreasing, and decreases the consumer to pay, so his demand curve is downward slope (negative). Until the marginal utility (MUX) remains positive, total utility increases, the MUX is zero, total utility is maximum.



99

0

20

40

60

80

100

1 2 3 54

Curba dispoziieimarginale de a plVti a

consumatorului

p (u.m.)

Q/ziFig. 1.12. - Curba dispoziiei

marginale de a plVti a consumatorului

D

D

n concluzie, un consumator i

maximizeaz utilitatea total prin ajustarea cantitii achiziionate din bunul X, pn cnd utilitatea marginal a ultimei uniti achiziionate devine egal cu zero.

O asemenea concluzie este ns valabil doar n cazul ipotezei de abunden, cnd nimic nu limiteaz posibilitile de consum. Consumatorul nu suport nici un cost, n sensul c nu trebuie s renune la nimic pentru a-i procura o unitate suplimentar din bunul X.

n ipoteza raritii ns, individul trebuie s arbitreze (aleag) ntre diferitele alternative posibile de consum, atunci cnd i maximizeaz utilitatea total (U).

Deoarece bunurile se schimb contra bani, problema consumatorului este de a repartiza un buget dat ntre diferitele bunuri de achiziionat. Cum poate el s-i ajusteze cheltuielile n aa fel nct s-i maximizeze utilitatea? n acest scop, el trebuie s compare utilitatea marginal a achiziionrii diferitelor bunuri i s-i cheltuiasc fiecare unitate monetar pentru acele bunuri, a cror utilitate marginal este cea mai mare.

S lum cazul unui consumator care trebuie s aleag ntre bunurile X i Y, care au preurile px i py. El i va maximiza utilitatea total atunci, cnd i va aloca venitul n aa fel ntre cele dou bunuri, nct

0

20

40

60

80

100

1 2 3 54

Curba dispoziieimarginale de a plVti a

consumatorului

p (u.m.)

Q/ziFig. 1.12. - Curba dispoziiei

marginale de a plVti a consumatorului

D

D

In conclusion, a consumer maximizing his total utility by adjusting the quantity of good X purchased until the last unit purchased marginal utility becomes zero. A conclusion is however also valid for the assumption of abundance, if nothing restricts consumption . The consumer does not bear any cost, meaning that should not stop at nothing to procure an additional unit of good X. But the rarity assumption, the individual must arbitrate (choose) between the various possible alternatives to drinking when his maximizes total utility (U). As goods are exchanged for money, consumer problem is to allocate a given budget between different goods purchased. How can he adjust its expenditure so as to maximize its usefulness? To this end, he must compare the marginal utility of purchasing various goods and to spend each monetary unit for those goods, whose marginal utility is highest. Take the case of a consumer who must choose between goods X and Y, which have prices px and py. It will maximize the



100

utilitatea suplimentar obinut prin consumul acelei cantiti de X pentru care s-a pltit o unitate monetar suplimentar devine egal cu utilitatea suplimentar obinut prin consumul acelei cantiti de Y pentru care s-a pltit aceeai unitate monetar adiional. n aceast situaie, spunem c utilitatea marginal pe o unitate monetar corespunztoare bunului X este egal cu utilitatea marginal pe o unitate monetar corespunztoare bunului Y. n acest caz, consumatorul este n situaie de echilibru, deoarece nu-i mai poate spori utilitatea total renunnd la cumprarea unui bun n favoarea celuilalt bun.

Deci, condiia de echilibru a consumatorului, respectiv de utilitate total maxim este:

Y

Y

X

X

pMU

pMU =

Ce se ntmpl dac preul bunului X

scade, ceteris paribus? n acest caz, avem:

Y

Y

X

X

pMU

pMU >

ceea ce nseamn c individul i va spori utilitatea consumnd mai mult X i mai puin Y. Dar dac se consum mai mult X, scade MUx, deci scade i utilitatea marginal pe unitatea monetar, pn cnd egalitatea anterioar va fi restabilit.

n concluzie, reducerea preului unui bun va determina, ceteris paribus, o cretere a cererii pentru bunul respectiv, deci curba cererii este descresctoare de la stnga spre dreapta.

De exemplu, dac MUx = 20, MUy = 25, px = 4 i py = 5, atunci:

5525

4205 =====

y

y

x

x

pMU

pMU

deci, consumatorul este n echilibru, adic i-a maximizat utilitatea total.

Dac px scade cu 2 u.m. i consumul

total utility when, will allocate income between two goods so that additional utility obtained by consuming quantities of X has been paid a further monetary unit is equal to the additional utility obtained from consumption of that quantity Y that additional money was paid the same unit. In this situation, we say that the marginal utility per unit money good X is equal to the marginal utility per unit money good Y. In this case, the consumer is in a state of equilibrium, because no longer can increase total utility by giving up the purchase of property for other property. So the consumer equilibrium condition, ie maximum total utility is:

Y

Y

X

X

pMU

pMU =

What if the asset price X decreases, ceteris paribus? In this case, we have:

Y

Y

X

X

pMU

pMU >

which means that the individual will enhance the usefulness consume more X and less Y. But if you consume more X , MUX decreases, so decreases and the marginal utility per unit money until earlier equality will be restored. Finally, a good price reduction would lead, ceteris paribus, a demand for the asset, so demand is decreasing curve from left to right.

For exemple, if MUx = 20, MUy =

25, px = 4 i py = 5, then :

5525

4205 =====

y

y

x

x

pMU

pMU

so, the consumer is in equilibrium, ie has maximized total utility. If px is reduced by 2 u.m. and X consumption changes, the monetary unit we have 20 / 2 = 10 units of MUx, MUy to only 5 units.



101

de X nu se schimb, pe unitate monetar avem 20/2 = 10 uniti de MUx, fa de numai 5 uniti MUy.

511

10 =>=leu

MUleu

MU yx

n aceste condiii, cheltuind o u.m.

adiional pentru bunul X, consumatorul i mrete utilitatea cu 10, dar dac aceeai unitate monetar o cheltuiete pentru bunul Y, utilitatea sa crete doar cu 5. Ca urmare, un consumator raional va cumpra bunul X i nu bunul Y. BIBLIOGRAFIE 1. ALBERT, M.,- Capitalism contra capitalism, Ed. Humanitas, Bucureti,1993;

2. BECKER, G.S.,- Comportamentul uman. O abordare economic, Ed. ALL, Bucureti, 1996;

3. BRAN, P. -Economica valorii, Ed. Economic, Bucureti, 2005;

4. BBI I., SILASI G., DU A. Macroeconomia Editura Orizonturi Universitare, Timioara, 2007;

5. CIUCUR D., GAVRIL ILIE, POPESCU CONSTANTIN, Economie (manual universitar), ASE, Editura Economic, Bucureti, 2005;

6. DIDIER, M., - Economie. Regulile jocului, Ed. Humanitas, Bucureti, 1994;

7. DOBROT, N. (coordonator) - Economie politic, Ed. Economic, Bucureti, 1997;

8. GALBRAITH, J. K., - tiina economic i interesul public, Ed. Politic, Bucureti, 1982;

9. HEYNE, P., - Modul economic de gndire, Ed. Didactic i Pedagogic, Bucureti, 1991;

10. SAMUELSON P., NORDHAUS, W., - Economie, Ed. Teora, Bucureti, 2000;

511

10 =>=leu

MUleu

MU yx

In these circumstances, additional spending mu for good x increases its usefulness to the consumer 10, but if one spends the same currency unit for good y, its usefulness increases only by 5. Therefore, a rational consumer will not buy good x and good y. BIBLIOGRAPHY 1. ALBERT, M.,- Capitalism versus Capitalism , Ed. Humanitas, Bucureti,1993;

2. BECKER, G.S.,- Human behavior. An economic approach, Ed. ALL, Bucureti, 1996;

3. BRAN, P. -Economica valorii, Ed. Economic, Bucureti, 2005;

4. BBI I., SILASI G., DU A. Macroeconomia Editura Orizonturi Universitare, Timioara, 2007;

5. CIUCUR D., GAVRIL ILIE, POPESCU CONSTANTIN, Economie (manual universitar), ASE, Editura Economic, Bucureti, 2005;

6. DIDIER, M., - Economy. Game Rules , Ed. Humanitas, Bucureti, 1994; 7. DOBROT, N. (coordonator) - Economie politic, Ed. Economic, Bucureti, 1997;

8. GALBRAITH, J. K., - Economics and public interest, Ed. Politic, Bucureti, 1982;

9. HEYNE, P., - Economic way of thinking , Ed. Didactic i Pedagogic, Bucureti, 1991;

10. SAMUELSON P., NORDHAUS, W., - Economy, Ed. Teora, Bucureti, 2000;



102

11. SILAI G., SRGHI N.,LOBON O. Microeconomia -n fie- - Editura Mirton, Timioara,2007;

12. ASE, Catedra de Economie i Politici Economice Economie - -Ediia a aptea Editura Economic, Bucureti, 2005;

11. SILAI G., SRGHI N.,LOBON O. Microeconomia -n fie- - Editura Mirton, Timioara,2007;

12. ASE, Catedra de Economie i Politici Economice Economie - -Ediia a aptea Editura Economic, Bucureti, 2005;

Cantitate (baton ciocolata) X

Utilitate marginal (utili) MUx

Utilitatea total (utili) Ux

Dispoziia de a plti a consumatorului

0 - 0 100 1 20 20 80 2 15 35 60 3 10 45 40 4 5 50 20 5 0 50 0

9 Ilie Babaita

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