f (long bien bac nhat theo We nk va x.
5.3.1.Sy tic Ong ben ngoai, t6i ttu hoa ttx nhan va t6i itu hoa xa ho
tu nhan (f' = + lx.xsk > f' k ) nen site tang throng nen kinh to tap trung se manh hon sac tang trung nen kinh to phi tap trung (y. >yd).
5.3.1. Sy tic Ong ben ngoai, t6i ttu hoa ttx nhan va t6i itu hoa xa hoi xa hoi
Neu to gia thiet rang \Ted quy mO theo doanh nghiep, nang suat quy mO (tu ban va lao clang) khOng tang twang thi sac san xua't bien to ban ding se suy giam va mO hinh se khOng tiep can den tang twang nOi sinh. Do vay can phai dui vao mo hinh cac nhan t6 ben ngoai de dat du9c nang suat tu ban khong d6i theo quy mO vi mO, bang each du kie'n truck su phi tang truing cua cac nang suat to ban theo quy mO doanh nghiep. Nhung lkic nay se khOng can nira str trung hop giirra t6i uu xa hOi va toi kru to nhan. 'MOt su dieu chinh don gian cua mO hinh tang throng tan c6 dien cho phep phan anh du9c lc& qua nay. Trong m6 hinh tang trung tan c6 dien vai da phat trien khoa h9c ky thuat co yeu t6 ngoai sinh, s6 lacing san pham binh quan tren dau ngued (q) phu thuOc vao lacing tu ban binh quan theo dau ngued (k) va phu thuOc vao su phat tridn khoa hoc ky thuat. Cac yeu to nay se cai thien hieu qua lao dOng (x).
= f(k,x) (5.7)
Nang suit tu ban binh quan theo dau nguai suy giam nhung nang suat cua tong town b6 lumg tu ban binh quan theo dau ngtrai va su phat tridn khoa hoc ky thu4t lai khOng dOi (dieu nay cho phep dat duqc mat su tang twang bao town cua s6 luting san pham theo dau ngued theo phuong thdc ngoai sinh).
Su phat tridn khoa h9c cong nghe x phu thuOc vao kho tang kin tilde du9c tich luy. Ta gia thi6t rang kho tang kien tilde nay tang va bang mire tang cua Wong tu ban binh quan theo dau ngued cua nen kinh te":
x(k) = k. Veri quy mO vi mO, ham san xuat se tuong Crng voi nang suit khOng dOi so vai 1u9ng tu ban:
Sire san xuat to ban bien khOng d6i nen to có six tang throng not sinh. Tuy nhien, do có six tac dOng cua cac yeu t6 ben ngoai nen khOng con nira sty trUng hqp gida tY 1Q tang twang cua nen kinh to phi tap trung va tY le tang trung t6i uu da dugc dtr
a)
Lai suat Sac san xuat to ban bien
• 'r6i uu cua cac 1-10 dan cu r — =
Toi uu coa cac doanh nghi0
f'(k)= r
T57 1e tang tru6ng a — r
Lai suit Sirc san xuat to ban bien
• b) b)
T6i uu cua cac h0 dan cu
T6i uu xa h0i
Toi uu cUa cac doanh nghi0
Ty 1 tang trir&ng y
Hinh 5.3. NhAn to ngoai canh, t6i ttu xa h6i va to1 tru to nhan
a) KhOng có nhan t6 ngoai canh tac Ong; b) Co nhan t6 ngoai canh tac dOng.
LY do rat don gian. Trong six tOi ixu hoa cua minh, doanh nghiep se can bang tY suat lo'i nhuan va sire san xuat bien tu ban tu nhan ma kh6ng tinh den tac dOng cua viec tang tu ban se lam tang sirc san xuat trong toan he thong doanh nghiep. Neu guy& dinh dau to duoc thirc thi theo ke hoach da de ra thi can phai tinh den sirc san xuat bien tu ban xa hOi. Skit san xuat nay cao hon srrc san xuat to nhan va 6'7 le tang twang ciia nen kinh to se tang len (hinh 5.3b).