📚 AS Eduqas Economics: Quick Formula & Theorem Handbook | AS Eduqas 经济：公式定理速查手册
This handbook brings together the essential formulas, equations and key theoretical relationships you need for the AS Eduqas Economics specification. Use it as a rapid revision tool to strengthen your quantitative analysis and diagram-based reasoning in both microeconomics and macroeconomics.
本手册汇集了AS Eduqas经济学课程所必需的核心公式、方程和关键理论关系，可作为快速复习工具，助你强化微观与宏观部分的量化分析和图形推理能力。
1. Demand, Supply and Market Equilibrium | 需求、供给与市场均衡
A linear demand function can be written as Qd = a − bP, where 'a' is the quantity demanded when the price is zero and 'b' reflects the responsiveness of quantity demanded to a change in price. The law of demand states that, ceteris paribus, as price rises, quantity demanded falls.
线性需求函数可表示为 Qd = a − bP，其中a是价格为零时的需求量，b反映了需求量对价格变动的敏感程度。需求定律认为，在其他条件不变时，价格上升，需求量下降。
A linear supply function is given by Qs = c + dP, where 'c' is an intercept term and 'd' is the slope coefficient. The law of supply asserts that, ceteris paribus, an increase in price leads to a rise in quantity supplied.
线性供给函数为 Qs = c + dP，c为截距项，d为斜率系数。供给定律指出，在其他条件不变时，价格上升会使供给量增加。
Market equilibrium occurs where quantity demanded equals quantity supplied: Qd = Qs. Solving simultaneously yields the equilibrium price P* and quantity Q*. Shifts in either curve alter the equilibrium outcome.
市场均衡出现在需求量等于供给量之处：Qd = Qs。联立求解可得到均衡价格 P* 与均衡数量 Q*。任何一条曲线的移动都会改变均衡结果。
| Factor | Effect on Demand | 中文影响 |
|---|---|---|
| Income (normal good) | Increase → demand shifts right | 收入增加需求右移 |
| Price of substitute | Rise → demand for good increases | 替代品价格上升，需求增加 |
| Technology (supply) | Improvement → supply shifts right | 技术进步，供给右移 |
| Costs of production | Rise → supply shifts left | 生产成本上升，供给左移 |
2. Price Elasticity of Demand (PED) | 需求价格弹性
PED measures the responsiveness of quantity demanded to a change in price. The basic formula is PED = %ΔQD ÷ %ΔP, where %ΔQD = (Q₂ − Q₁)/Q₁ × 100 and %ΔP = (P₂ − P₁)/P₁ × 100. For greater accuracy across an arc, Eduqas uses the midpoint method: %ΔQD = (Q₂ − Q₁) ÷ [(Q₁ + Q₂)/2] × 100, and equivalently for price.
PED衡量需求量对价格变化的反应程度，基本公式为 PED = %ΔQD ÷ %ΔP，其中 %ΔQD = (Q₂ − Q₁)/Q₁ × 100，%ΔP = (P₂ − P₁)/P₁ × 100。为提高弧上的计算精度，Eduqas采用中点法：%ΔQD = (Q₂ − Q₁) ÷ [(Q₁ + Q₂)/2] × 100，价格同理。
| |PED| Value | Interpretation | 中文解释 |
|---|---|---|
| > 1 | Elastic – responsive | 富有弹性 |
| < 1 | Inelastic – unresponsive | 缺乏弹性 |
| = 1 | Unit elastic | 单位弹性 |
| = 0 | Perfectly inelastic | 完全无弹性 |
| = ∞ | Perfectly elastic | 完全弹性 |
The total revenue test links PED to revenue: if demand is elastic (|PED| > 1), a price cut raises total revenue; if inelastic (|PED| < 1), a price cut lowers revenue. The relationship is crucial for pricing strategies.
总收入检验将PED与收入挂钩：需求富有弹性时，降价可提高总收入；缺乏弹性时，降价反而降低总收入。这一关系对企业定价至关重要。
3. Price Elasticity of Supply (PES) | 供给价格弹性
PES is given by PES = %ΔQS ÷ %ΔP, again using the midpoint formula for precision. PES tells us how easily output can be adjusted in response to a price change.
供给价格弹性公式为 PES = %ΔQS ÷ %ΔP，同样使用中点法计算以保证精确。PES表明产量对价格变动反应的灵敏程度。
e time period (longer run → more elastic), the level of spare capacity, the ease of factor
Published by TutorHao | AS Economics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图