6-Mavzu bayoni Naflilik nazariyasining asosiy qoidalari. Iste`molchi tanlovi

29-rasm. Chekli almashtirish normasi.⁷
Befarqlik egri chizig`i koordinata boshiga nisbatan botiq bo`lgani uchun, MRS bir ne`mat bilan boshqa ne`matni almashtirish oshib borgan sari kamayib boradi. 29-rasmda o`qi bo`yicha ajratilgan  ni o`qi bo`yicha ajratilgan  ga nisbatan chekli almashtirish normasini beradi:

;

- bilan ni chekli almashtirish normasi.

befarqlik egri chizig`ining har qanday nuqtasida, shu nuqtadan o`tgan chiziqning tangens burchagi yotiqligining absolyut qiymatiga teng. Befarqlik egri chizig`ining tangens burchagi yotiqligi manfiy bo`lgani uchun manfiy bo`ladi. Lekin, musbat bo`lib, u burchak yotiqligining absolyut qiymati bo`yicha olinadi.

Agar funktsiya uzluksiz bo`lsa,

.

Masalan, kitobga va ta bananga teng bo`lsa, bo`ladi va iste`molchi bitta kitob uchun uchta bananni berishga tayyor. Ko`rsatish mumkinki, bu erda 3 ta banandan olinadigan naf bitta kitobdan olinadigan nafga teng.

Boshqa tomondan naflik funktsiyasi dan to`liq differentsial olsak:

.

va larni shunday tanlash mumkinki, natijada bo`ladi. U holda quyidagini yozishimiz mumkin:

bu erda va .

Demak, ikkinchi ne`matni birinchi ne`mat bilan befarqlik egri chizig`ining har bir nuqtasidagi chekli almashtirish normasi , ne`matlarning shu nuqtadagi chekli nafliklari nisbatiga teng.

“An indifference map describes a person's preferences concerning various combinations of goods and services. But preferences do not explain all of consumer behavior. Individual choices are also affected by budget constraints, which limit people's ability to consume in light of the prices they must pay for various goods and services”⁸.