demand and supply

MUV curve is downward sloping curve!!(=slope down from left to right)


In marginal use value approach, 係因為假設人擁有一樣物品的數量愈多, 對佢的邊際價值下降. This is the Law of diminishing marginal use value.

The downward sloping MUV curve equals to a downward sloping demand curve base on the postulate of constraint maximization.



In indifference approach, when price of Good X drops, 如果個-ve substitution <+ve income effect,
derive 到條downward sloping money income constant demand curve, and downward sloping real income constant demand curve.

即係只要個-ve substitution 唔好大過 -ve income effect, derive 到條upward sloping money income constant demand curve, 咁demand curve 都係downward sloping.