Chng IV: L thuyt hnh vi ngi sn xutI. L thuyt ngi sn xut:1. Hm sn xut:1.1. Hm sn xut: xc nh sn lng ti a c th t c sn xut t bt k khi lng cho trc no ca u vo vi mt trnh cng ngh nht nh .Q max = F (L, K) ( L: labour; K : capital)u vo, u ra

Hm sn xut ph bin nht ca cc doanh nghip l hm sn xut Cobb - Douglas c dng: Q = A.K.L (; > 0, < 1) +A l hng s , tu thuc vo n v o lng , u ra, u vo , biu th trnh cng ngh sn xut . +, l hng s cho bit tm quan trng tng i ca lao ng v vn trong qu trnh sn xut.+ Mi ngnh sn xut v cng ngh khc nhau th , khc nhau.+ , biu th hiu sut theo qui m sn xut ca hng.

=> Vy hiu sut: l mi tng quan gia u vo v ra.* Nu: + < 1: Hm sn xut biu th hiu sut gim theo qui m ( vo tng nhiu hn u ra) + = 1: Hm sn xut biu th hiu sut khng i theo qui m. + > 1: Hm sn xut biu th hiu sut tng theo qui m (hu ht cc hng c iu ny).

2. Sn xut trong ngn hn: (sn xut vi 1 u vo bin i)Sn xut ngn hn l khong thi gian m hng sn xut khng th thay i tt c cc u vo, c t nht l 1 u vo c nh.MPPL(Marginal physical product): l s thay i ca s lng sn phm u ra khi c s thay i ca 1 n v u vo lao ng (L). MPPL = Q/L = Q'(L)APPL: sn phm hin vt bnh qun (Average physical product): l s lng sn phm u ra tnh cho 1 n v u vo lao ng. APPL = Q/L

K

L

Q

MPPL

APPL

1

0

0

0

0

1

1

10

10

10

1

2

21

11

10,5

1

3

31

10

10,33

1

4

39

8

9,75

1

5

42

3

8,4

1

6

42

0

7

1

7

40

-2

5,71

Vi K khng i s lao ng tng ln (L tng) =>cho s cng nhn trn mt my gim v tng ln n mt mc no s khin cho nh xng cng khng ch, thiu my mc .. cn tr thao tc sn xut => NSL gim => Q gim => MPPL gim dn khi L tng ln do mi L tng gp thm 1 lng gim dn vo qu trnh SX. iu ny ph bin vi mi hng => cc nh kinh t khc khi qut thnh qui lut hiu sut gim dn. Nguyn nhn:

" Sn phm hin vt cn bin ca 1 u vo bin i s gim dn khi hng tng cng s dng u vo bin i ".Nguyn nhn l do khi L tng m K khng i dn n tnh trng khng hp l gia K v L khin nng sut lao ng gim dn => NSL cn bin gim dn.Ch : MPPL qua im max ca APPL v APPL = Q/L => (APPL)' = Qui lut c pht biu nh sau:

3. Sn xut di hn : Longterm production (Sn xut vi 2 u vo bin i)Sn xut di hn l khong thi gian lm cho tt c cc u vo ca hng bin i.3.1. ng ng lng (Isoquant) ng ng lng m t nhng kt hp u vo khc nhau em li cng 1 mc sn lng.

c im ca ng ng lng- Cc ng ng lng dc xung t tri sang phi v li so vi gc to .- Mt ng ng lng th hin 1 mc sn lng nht nh, cc ng ng lng khc nhau c mc sn lng khc nhau.- ng ng lng cng xa gc to cng c mc sn lng cao hn.- Cc ng ng lng khng th ct nhau - dc ca ng ng lng = - K/L

dc ca ng ng lng phn nh t l thay th k thut cn bin ca cc yu t u vo l gim dn=> Ti sao K /L gim dn?K/L = MRTS (Marginal rates of technicalsubstitution)Vi 1 lng L tng khng i , K ngy cng gim i iu ny xy ra do qui lut hiu sut gim dn chi phi. Nu di chuyn trn ng ng lng, L tng ln mt lng nht nh, lc ny khi L tng ln theo qui lut hiu sut gim dn s khin MPPl gim xung, tri li khi K gim i khin cho MPPk tng ln, dn n tng mt lng L nh c cng ngy ch cn gim t hn mt lng K no => MRTS gim dn.

dc ca ng ng lng phn nh t l thay th k thut cn bin ca cc yu t u vo l gim dn. Ti sao K /L gim dn?K/L = MRTS (Marginal rates of technicalsubstitution)Khi L tng MPPl gim m K gim th MPPk tng (qui lut hiu sut gim dn). Nn tng mt lng L nh ban u (m mc sn lng u ra vn khng i) th ngy cng ch cn gim mt lng K t hn MRTS gim dn. K . MPPk + L . MPPl = 0 - K /L = MPPl/MPPk

K . MPPk + L . MPPl = 0

Mt s ng ng lng c bit* ng ng lng l ng thng

* ng ng lng c dng ch L

3.2. ng ng ph (Iso cost)ng ng ph th hin nhng kt hp u vo khc nhau m hng c th mua c vi mt tng cho ph cho trc.Phng trnh: L.w + K.r = TC (1)K: t bn; w: tin lng; L: lao ng;r: tin thu t bn (1) => K =

3. La chn kt hp u vo ti u:

II. Chi ph sn xut

1. Chi ph ngn hnFC (fixed cost) l nhng chi ph khng i khi mc sn lng thay i 1.1. Ch ph c nh ch ph bin i, tng chi phVC (variable cost) l nhng chi ph thay i khi mc sn lng thay i: nguyn vt liu, nhn cng..TC (total cost) l ton b chi ph c nh v bin i sn xut ra mc sn lng. TC = FC + VC

TC = FC + VC

1.2. Chi ph bnh qun AFC: (Average fixed cost) AFC = FC/ Q

AVC (Average variable cost) AVC = VC/ Q ATC (Average total cost) ATC = TC / Q ATC = AFC + AVC

Hnh biu din AFC, AVC, ATC

III. Ch ph kinh t v chi ph k ton1. Chi ph kinh t = CP tng minh + CP n* Chi ph tng (explicit):* Chi ph n (implicit):2. Chi ph k ton

III. Li nhun*Khi nim li nhun * Li nhun kinh t* Li nhun k ton* Cc nhn t nh hng ti li nhun LN = TR TC = P . Q ATC . Q = Q. ( P - ATC )

Chng V: Th trng cnh tranh v c quynI. Th trng v phn loi th trng* Khi nim th trng* Phn loi th trng* Cc tiu thc phn loi

II. Th trng cnh tranh hon ho ( Perfect competitive market)1. c im 2. ng cu v ng doanh thu cn bin Hng chp nhn gi sn c trn th trng nn ng cu hng CTHH l ng nm ngang, ti mc gi cn bng ca th trng

Hng bn mi sn phm mc gi Pe=> P = MR => ng doanh thu cn bin trng vi ng cu* Chng minh: Q* ti P = MC hng t li nhun ti a* Ch : iu kin c li nhun P > ATCiu kin ti a ho li nhun P = MC

4. im ho vn, ng ca hay tip tc sn xut* im ho vnTR = TC = FC + VCP.Q = FC + AVC. QQhv = FC/(P - AVC) * im ng ca hay tip tc sn xut

5. ng cung ca CTHH v ng cung ngnh* Hng CTHH c P = MC nn ng cung ca hng CTHH trng vi ng MC

5. Thng d sn xut (Producer surplus)

* Mi quan h gia thng d sn xut v li nhun:PS = TR - VC = TR - ( TC -FC )=> PS = TR - TC + FC = + FC=> PS c mi quan h t l thun vi v FC

III. Th trng c quyn (Monopoly market) 1. Khi nim 2. c im 3. Nguyn nhn: 4. ng cu v ng doanh thu cn bin

TR = P . Q => AR = TR/Q = P

P

Q

TR

MR

AR

Nhn xt

6

0

-

-

-

5

1

5

5< P

5 = P

P = MR

4

2

8

3< P

4 = P

P> MR

3

3

9

1< P

3 = P

-

2

4

8

-1

5. Quyt nh sn xut ca nh c quyn bn* Nh c quyn ti a ha li nhun ti mc sn lng Q* ti MR = MC*Gi bn P* c xc nh trn ng cu D * Li nhun cc i l: max = (P* - ATC). Q*

* Hng Q khng c ng cung hay ni cch khc khng c mi quan h hm s gia P v Qs.* Trong Q s dch chuyn ca ng cu c th lm P thay i Q gi nguyn, hoc P gi nguyn Q thay i hoc c P v Q u thay i.

6. Sc mnh c quyn bnQ bn t P > MC=> c sc mnh Q bn Abba Lerner a ra L nm 1934 L = P - MC ; (0 < L < 1) P * Ch : - L >> => sc mnh Q cng ln - L = 0 => P = MC, khng c sc mnh Q

7. Phn bit gi: (Price Discrimination)7.1. Phn bit gi hon ho (cp 1)

7.2. Phn bit gi cp 2:

7.3. Phn bit gi cp 3:MR1 =MR2 =MRtt; Q1 + Q2 = Qtt

7.4. t gi theo thi gian (thi k)

7.5. t gi theo thi im (cao im)

7.6. t gi hai phn:P*CS

IV. Th trng cnh tranh khng hon ho(Imperfect competition market)1. Cnh tranh c quyn* Khi nim: L th trng c nhiu hng cung cp v bn sn phm nhng sn phm ca mi hng c s phn bit* c im:- C nhiu ngi bn- Sn phm khc nhau (d bit ho)

-Mi hng l ngi sn xut duy nht i vi sn phm ca mnh nn c sc mnh th trng tuy nhin L ca hng CTQ thp hn so vi Q v c nhiu hng khc sn xut cc sn phm c kh nng thay th- Vic ra nhp hay rt khi th trng l tng i d- Hnh thc cnh tranh ch yu l qung co d bit ho sn phm camnh, hu mi, ...

* Nguyn nhn dn n c quyn:- S qui nh ca Chnh ph; v d in lc- Do iu kin t nhin cho php; Kim Bi...- Cc hng dng ln hng ro ngn cn s gia nhp ca hng khc thng qua: tnh hiu sut tng theo qui m, bng pht mnh sng ch, kim sot yu t u vo, lao ng, hay do qung co lin tc to tm l tiu dng. - S tc ng qua li gia cc hng (hp tc, cu kt); VD th trng du m CTHH=>CTQ

* ng cu ca hng CTQ- ng cu ca hng CTQ chnh l ng cu th trng v tuy th trng c nhiu hng sx nhng cc sn phm khc nhau- ng cu ca hng CTQ dc xung t tri sang phi tuy nhin thoi hn so vi Q * Xc P*,Q*, li nhun ca hng CTQ Q* xc nh ti MR =MC, P* xc inh trn ng cu CTQ c P thp hn v Q cao hn so vi Q => L ca CTQ cng thp hn so vi Q

* Cn bng di hn ca hng CTQA

- Ngn hn LN>0 => hng nhp ngnh=> th phn gim => D dch chuyn sang tri tip xc LAC =>LN = 0 t cn bng di hn- So snh cn bng DN ca CTHH v CTQ+ Ging: NH c LN > 0 => cc hng nhp ngnh, cui cng t cn bng DH khi LN = 0 + Khc: CTHH cung tng S d/c sang phi, CTQ cu gim, D dch chuyn sang tri * Ch : Trong di hn hng CTQ c th phi sn xut vi cng sut tha?

2. Th trng c quyn tp on2.1. Khi nim: L th trng ch c mt s hng sn xut v bn sn phm. Cc sn phm ging nhau gi l Q T thun tu, sn phm khc nhau gi l QT phn bit2.2. c im:- C 1 s hng trn th trng nhng c qui m rt ln

- Cc hng ph thuc ln nhau, mt hng ra quyt nh phi cn nhc phn ng ca cc i th (phn ng nhanh qua gi hoc phn ng chm bng vic a ra s/p mi- Hng ro ra nhp rt cao nn s gia nhp ngnh l rt kh thng qua: tnh kinh t theo qui m, bn quyn hoc b cc hng c lin kt tr a

2.3.M hnh ng cu gy khc trong th trng CTQ (The kinked demand curve model)* Cc hng QT u bit rng:+ N mt hng tng gi th cc hng cn li khng tng gi+ Nu mt hng gim gi th cc hng cong li s phi gim ga theo

- c im c bn khi ng cu gy khc th ng doanh thu cn bin MR t qung (gin on ti mc sn lng Q*)- Sn lng t 0 => Q* hng c ng cu thoi (D1, MR1), cu co dn ln theo gi - Sn lng t Q* tr ln hng c ng cu dc (D2, MR2), cu co dn t theo giT cc c im ny nn hng QT c ng cu gy khc l kt hp ca D1v D2

- Ti Q* MR b t qung, hay c khong trng gi l lp m chi ph cho php hng gi c gi v sn lng khi chi ph cn bin MC thay i trong lp m.- Lp m chi ph to cho cc hng QT c kh nng gi s n nh trong gi v sn lng ti u, to nn tnh cng nhc ca gi v sn lng.

2.4. L thuyt tr chi:- Nu cc hng hp tc th s c hp ng rng buc khin h c th hoch nh nhng chin lc chung (v ngc li). - L thuyt tr chi m t nhng quyt nh thng minh nht ca cc hng ph thuc ln nhau. Nhng tr chi kinh t tin hnh mt cch hp tc hoc khng hp tc.- Nu hp tc th P cao v Q gim, li nhun tng tuy nhin thng khng chc chn, do cc hng thng ph cam kt tng li nhun cho ring mnh.

Chng VI: Th trng sc lao ng

I. Cung sc lao ng1. Khi nim:

2. Nhng nhn t nh hng n cung sc lao ng2.1. p lc v kinh t2.2. p lc v mt tm l x hi2.3. S bt buc phi lm vic2.4. Gii hn v thi gian t nhin2.5. ch li cn bin ca lao ng v ngh ngi- ch li cn bin ca ngh ngi l lng ch li tng thm do mt gi ngh ngi b sung mang li (MUnn)

Ich li cn bin ca lao ng l ch li tng thm t vic tiu dng nhng hng ho dch v c th mua c bng tin cng ca 1 gi lao ng b sung. (MUlv)MUnn v MUlv cng tun theo qui lut ch li cn bin gim dn Thi gian lao ng ti u xy ra ti im m ch li cn bin bng chi ph cn bin. * im xc nh thi gian lao ng ti u l im tho mn: MUlv = MClv m MClv = MUnn => im l im ch li cn bin ca lm vic bng ch li cn bin ca ngh ngi: MUlv = MUnn

MUlv = MClv m MClv = MUnn

3. ng cung lao ng vng v pha sau (Backward-bending supply curve)

II. Cu v lao ng1. Khi nim: - Cu v lao ng l dn xut, th pht, pht sinh (derived demand) n ph thuc vo sn lng ca doanh nghip.

2. Sn phm doanh thu cn bin ca lao ng: MRPl- Marginal Revenue Product of Labour* Sn phm cn bin ca lao ng (Marginal product of labour)MRPl = Q / L = QlMPl tun theo qui lut nng sut cn bin gim dn * MRPl = TR / L= MR. MPL* CTHH: MR = P => MRPL = P . MPL* Q: MR # P => MRPL = MR.MPL # P.MPL

Chng VII: S trc trc ca th trng v vai tr iu tit ca Chnh phI.S trc trc ca th trng

1. Th trng cnh tranh khng hon ho

- S trc trc ca th trng gy nn mt khng cho x hi (DWL: Dead weight loss)- Xut hin cc chi ph khng c li cho nn kinh t: qung co, vn ng hnh lang...2. nh hng ngoi ng (externality)* Khi no xut hin nh hng ngoi ng: khi mt hot ng tiu dng hay sn xut c tc ng i vi cc hot ng tiu dng hay sn xut khc.* C 2 loi nh hng ngoi ng:

2.1. nh hng ngoi ng tiu cc:khi mt hot ng ca mt bn p t nhng chi ph cho mt bn khc * V d: xt nh hng ngoi ng tiu cc do nhim t vic sn xut sn tng hp (gi s y l mt ngnh sn xut trong th trng CTHH). MSC: Marginal social cost- chi ph cn bin ca x hi do c nh hng ngoi ngMEC: Marginal externality cost- chi ph cn bin ngoi ngMSC = MC + MEC

MEC dc ln t 0 v khng sn xut khng c nh hngTi B cha tnh n MEC nn sn xut l Q2, P2; Ti A c tnh n MEC => P = MSC, sn xut Pe,Qe

2.1. nh hng ngoi ng tch cc: Xut hin khi hot ng cu mt bn lm li cho mt bn khc * V d: hng ho cng cng, hot ng quc phng, an ninh, khu vui chi cng vin, vn hoa cng cng,..Li ch cn bin ca x hi: MSB Marginal social benefit l tng li ch m thc t XH thu c t thm mt nh trng hoa. Li ch cn bin ngoi ng: (MEB: Marginal externality benefit) l ch li thc s thu c t vic c thm mt nh na trng hoaMSB = MU + MEBCP cn bin(MC): l chi ph thm mt h gia nh trng hoa

Ti A cha tnh n MEU sn xut ti QaTi B tnh n MEU khuyn khch tng Q t Qa=> QbTam gic ABC l nh hng ngoi ng tch cc mang li

3. S tn ti ca hng ha cng cng (Public goods):3.1.Hng ho t nhn: L cc hng ho dch v c mua bn bnh thng trn th trng v vic tiu dng ca ngi ny loi tr vic tiu dng ca ngi khc. 2 c im l: c th loi b (excludabitity)v c th gim bt (disminishability): ct tc, ti vi...3.2. Hng ho cng cng (Public goods): Hng ho cng cng l nhng hng ho dch v m vic tiu dng ca ngi ny khng loi tr s tiu dng ca ngi khc. * V d: hot ng quc phng, bo v tng zn, cng vin...Trc trc do khng p ng c li ch ring m cho tt c Trc trc 2 gi bng 0 nn lung tiu dng l v cng ln

* Hng ho cng cng cng gy nn mt tnh trng l s trng ch, ni vo Nh nc ca nhng k n khng, khng chu u t hoc ph hoi hay s dng lng ph cc hng ho cng cng. * v d: qui nh khng c ph hoi cy ci nhng nhiu ngi c o hoa mang v nh trng ri li Nh nc mang hoa n trng li.

=> khc phc s trc trc ny ny cn c s phi hp tp th; s hp tc gia cc c nhn v tp th c th t c cc kt qu nh mong mun. Mt x hi cng vn minh th cng c nhiu hng ho cng cng.