From the perspective of elasticity theory, "cheap grain hurts farmers" means that the price of goods with inelastic demand changes in the same direction as the total income. Due to the inelastic demand for agricultural products, a bumper harvest will reduce the prices of agricultural products and the total income of farmers. Due to the elasticity of supply and demand of agricultural products and the importance of agricultural products in the national economy, various countries have successively formulated various measures to stabilize the prices of agricultural products, such as "supporting prices", "limiting cultivated area, controlling supply", "subsidies" and "futures market", in order to maintain social stability. Other necessities with inelastic demand have similar practices.

Basic classification of elasticity theory

Demand elasticity includes:

① _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

For example, if the price of a product goes up 1% and the sales volume goes down 1.5%, the elasticity of this product is 1.5. There are five kinds of elasticity of demand: greater than 1, less than 1, equal to 1, and equal to zero and infinity, respectively, indicating that the change of demand is greater than, less than, and equal to the change of price, or the demand will not change no matter how the price changes, or the slight change of price will cause the infinite change of demand.

② _ Staff Bath: I returned to the male in the Tang Dynasty, and the staff radon was directly taken from the magpie in Lake τ.

(3) _ Wandering in the exquisite bath: I am eager to restore my childhood to the Tang Dynasty, and I am eager to restore my childhood to the Tang Dynasty. Tang Fang is addicted to it, and I am eager to cure it from τ Tangque.

Supply elasticity includes supply price elasticity and supply cross elasticity. Supply (price) elasticity is an index to measure the response degree of a commodity's supply to its own price change, which is calculated by dividing the percentage change of supply by the percentage change of price.

Demand elasticity and supply elasticity can be divided into point elasticity, arc elasticity and general method. Point elasticity is the elasticity Edp=(dQ/dP)*(P/Q) of a point on the demand curve or supply curve, and arc elasticity is the arc elasticity between two points on the demand curve or supply curve, also known as the midpoint method, (Q2-q1)/[(Q2+q1)/2]/(P2-. General formula: △ q * p/△ p * q. (P stands for price and Q stands for demand and supply)