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.

" 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 di hn l khong thi gian lm tt c cc u vo cu hng bin i.3.1. ng ng lng (Iso quant)M t nhng kt hp u vo khc nhau em li cng mc sn lng nh nhau* c im:MRTS (Marginal rate of technical substitution) gim dn?

K . MPPk + L . MPPl = 0Ph bin ng ng lng c MRTS gim dn nn c hnh dng sau

* Mt s ng ng lng c bit

2.2. ng ng ph (iso cost)

3. La chn kt hp u vo ti u:

CMR: Di hn hng c kh nng ti thiu ho chi ph sn xut hn trong ngn hn (w, r khng i)

II. Chi ph sn xut

1. Chi ph ngn hn

FC (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 = AFC + AVCATC (Average total cost) ATC = TC / Q

1.3. Chi ph c n bin (Marginal cost)L s thay i ca tng chi ph khi c s thay i cu mt n v sn lng u raMC = TC / Q = TCqMC c hnh ch U v nh hng ca qui lut hiu sut gim dn.CMR: MC i qua im cc tiu ca AVC v ATC ?

2. Chi ph di hn (long term total cost)2.1. Tng chi ph di hn (LTC: Longterm total cost)L ton b chi ph sn xut ra mt mc sn lng nht nhQ1: TC1 = K1.r1 + L1.w1Q2: TC2 = K1.r1 + L2.w2Q2: TC2 = K2.r2 + L2.w2

2. 2. Chi ph bnh qun di hn (LAC: (Longterm average cost)L tng chi ph di hn tnh trn mt n v u raLAC = LTC/QTrong ngn hn qui lut hiu sut gim dn chi phi nhng trong di hn chu s chi phi ca qui lut hiu sut theo qui m.

Hiu sut tng theo qui m

Hiu sut gim theo qui m

Hiu sut khng i theo qui m

a s LAC hnh ch U* Nguyn nhn:Hiu sut tng theo qui mHiu sut gim theo qui m

2.3. Chi ph cn bin di hn( LMC: Longterm marginal cost)* Khi nim: L s thay i ca tng chi ph di hn khi c s thay i ca mt n v u raHnh dng: Tu theo hng c tnh trng hiu sut theo qui m nh th no:LMC = LTC / Q = (LTC)q

Hiu sut tng theo qui m: LMC dc xung v nm di LAC

Hiu sut gim theo qui m: LMC dc ln v nm trn LAC

Hiu sut khng i theo qui m

Khi LAC hnh ch U: LMC qua im cc tiu cu LAC

2.4. Mi quan h gia SATC v LATC

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 nhun1. Khi nim v cc nhn t nh hng n li nhun -Li nhun kinh t = TR - TC kt - Li nhun k ton = TR - TC kton* Cc nhn t nh hng ti li nhun LN = TR TC = P . Q ATC . Q = Q. ( P - ATC ) * Khi nim

2. Ti a ho li nhun:* Doanh thu cn bin MR (Marginal Revenue):L s thay i ca tng doanh thu khi c s thay i camt n v u ra. MR = TR / Q = (TR)q or TRq+1 - TRqHng phi sn xut mc sn lng bao nhiu li nhun () cc i ?

Mc sn lng ti a ho li nhun l khi Q thay i th li nhun khng thay i / Q = 0 TR - TC / Q = 0 MR = MCTi mc sn lng Q* ti MR = MC hng t li nhun cc i

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)*Khi nim:

* 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 CTQ

- 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 cn 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 ngI. 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 nhin Mt ngy ch c 24 gi = TGlv + TGnn => la chn TGlv v TGnn cho ti u *ch li cn bin ca ngh ngi: MUnn

*Ich li cn bin ca lm vic: MUlvMUnn v MUlv cng tun theo qui lut MU gim dn t* xc nh MUlv = MClv * im xc nh thi gian lao ng ti u l im tho mn: MUlv = MClv m MClv = MUnn => t* c xc nh ti im m ch li cn bin ca lm vic bng ch li cn bin ca ngh ngi.MUlv tng => t tng, ngc li MUlv gim t gim

MUlv = MClv m MClv = MUnn

* Ch : V cc nhn t ni sinh v ngoi sinh (Movement along the supply curve)

(Shift of supply curve)

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

MRPL l mt ng dc xung t tri sang phi do qui lut hiu sut cn bin gim dn chi phi. T c im ca th trng Q c gi cao hn MC nn ng MRPl th trng Q dc hn v nm di ng MRPl trong th trng CTHH. MR= MC m P > MC => P > MR v P.MPl > MR. MPl=> cng mt mc lng th hng Q bao gi cng thu t nhn cng hn so vi hng CTHH.

3. Nguyn tc la chn ti u trong T2 SLMRPl > W => hng nn thu thm lao ng MRPl < W => hng khng nn thu thm lao ng MRPl = W => lc ny hng t c la chn ti u trong vic thu lao ng, hng nn dng li s lng lao ng ny

III. Cn bng trong th trng lao ngTrong th trng sc lao ng CTHH khi mt hng mun thu lao ng hng phi chp nhn mc gi tin cng sn c trn th trng. C ngha l mc tin cng c hnh thnh sn trn th trng=> ng CUNG i vi 1 hng thu lao ng trong th trng CTHH l mt ng co dn hon ton => nm ngang v song song vi trc honh) (ng cu l MRPL)

Ti mc thu lao ng ti u L* ta c mc lng bng sn phm hin vt cn bin We = MRPl

2. im cn bng trong T2 L phi cnh tranh2.1. Th trng c quyn mua Trong T2 ny DN l ngi thu L duy nht trn th trng nn ta c ng cu ca hng chnh l ng cu cu th trng. ng cung ca th trng cng chnh l ng cung L vi hng. * Mt s khi nim:

Tng chi tiu ca L (Total expenditure labour)

TEl = W. L (tin cng nhn vi s lng lao ng )

Tng chi tiu ca lao ng: Total expenditure labourMEl = TE / L L s thay i tng chi tiu lao ng khi c s thay i ca mt n v u vo lao ng.

MEl nm trn ng Sl Do Sl ch phn nh mc lng ca lao ng; cn MEl phn nh chi ph thc t phi tr khi thu thm mt l bao gm c lng v cc CP # nh bo him...L* l s L thu ti u xc nh l giao ca MEl v MRPl (=Dl)W T2 L QM bng t L* trn ng cung Sl v l mc lng W*. thp hn mc lng khi th trng lao ng l cnh tranh (xc nh bng giao ca Sl v Dl).

Hnh minh ho xc nh L* v W* trong T2 QM

2.2. Th trng SL Q bn (Trade Union)Mun tin cng l max , mc L (L1) xc inh ti im MR giao vi Sl, v t L1 trn ng cu Dl ta c mc lng rt cao W1.Mun ti a ho s L c thu th nghip on s chn ti im L*,W* l giao ca Sl v DlMun ti a ho doanh thu (TR max), ngha l tng tin lng l ln nht th nghip on s chn im m MR = 0, ngha l L2 v W2.

Hnh minh ho quyt nh ca nghip on trong T2 QB

2.3. c quyn song phng* Khi nim: c quyn song phng xy ra khi trn th trng xut hin c c quyn bn v c quyn mua sc lao ng.* c quyn bn: im A, L2 = MR x Sl, cn gi W2 xc inh trn ng cung h mong mun t c im ti u l (W2 , L2).* c quyn mua: im B, L1 =MEL x DL, mc lng W1 xc nh trn Sl, Im (W1, L1).

Hnh minh ho Q song phng

Nu 2 bn khng bn no c sc mnh tuyt i th mc lng s giao ng trong khong t W1 n W2. Nu sc mnh c quyn mua > c quyn bn th mc lng s gn vi W1 v ngc li nu nu c quyn mua < c quyn bn th mc lng s gn vi W2. Trong trng hp sc mnh c quyn mua v c quyn bn l ngang nhau th th trng s xc nh im ti u ti kt hp (L*, W*).

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.