# AP Microeconomics Review Notes

## Chapter 3 Production Function and Cost Curves

### Production function 生产函数

#### Law of diminishing marginal return 边际收益递减

• When additional units of a resource are added to a fixed resource, beyond some point the marginal
product falls.
• 一种投入的边际产量随着投入品的增加而减少。

#### Graphs of production function 生产函数图像

• Increasing marginal returns – Input↑ MP↑
• Diminishing marginal returns – Input↑ MP↓
• Negative marginal returns – Input↑ MP becomes negative
• 边际收益递增 投入增加 边际产量增加
• 边际收益递减 投入增加 边际产量降低
• 负的边际收益 投入增加 边际产量变为负数

### Short-run production costs 短期生产成本

• Short run is a period of time when supply cannot fully adjust to changes in demand due to fixed
resources.
• 在短期，由于资源固定，供给不能完全适应需求变化。

#### Total fixed costs (TFC) vs Total variable costs (TVC) vs Total costs (TC) 总固定成本 总可变成本 总成本

• Total fixed costs (TFC) are those that do not vary with changes in output. In the short run these costs stay constant. When a firm's output is zero, these costs have to be paid.
• 总固定成本是不随着产量变化而变动的成本。在短期这些成本保持不变。当公司的产量为0，这些成本仍然需要支付。
• Total variable costs (TVC) vary as output changes. When there is no production, variable costs equal zero.
• 总可变成本在产量变化的时候变化。当产量为0时，可变成本为0。
• TC = TFC + TVC

#### Average fixed costs (AFC) vs Average variable costs (AVC) vs Average total costs (ATC) vs Marginal cost (MC) 平均总成本 平均可变成本 平均总成本 边际成本

AFC = \dfrac{TFC}{Q}

AVC = \dfrac{TVC}{Q}

ATC = \dfrac{TC}{Q}

MC = \dfrac{\Delta TC}{\Delta Q}

#### Cost curves 成本曲线

• Specialization and Division of labor → Decreasing MC
• Diminishing marginal return → Increasing MC
• MC curve intersects both the AVC and ATC at its minimum points.
• 专业化和分工 降低边际成本MC
• 边际收益递减 增加边际成本MC
• 边际成本曲线穿过AVC和ATC的最低点

#### Taxes and shifting cost curves 税和成本曲线的移动

Per unit taxes (Excise tax) 消费税

Lump-sum taxes 一次性征税

#### Production function vs Cost curves 生产函数和成本曲线的关系

MP vs MC
• As MP is falling, MC is rising.
• As MP is rising, MC is falling.
• When MP is highest, MC is lowest

b. AP vs AVC
• As AP is falling, AVC is rising.
• As AP is rising, AVC is falling.
• When AP is highest, AVC is lowest.

### Long-run production costs 长期的生产成本

• Long run is a period of time when supply can fully adjust to changes in demand as no production input is
fixed.
• 由于长期没有生产投入是固定的，可以充分的根据需求调整。
• The long-run average total cost curve (LRATC) shows the relationship between output and ATC when
fixed cost has been chosen to minimize ATC for each level of output.
• 长期LRATC展示了产量和ATC的关系当固定成本是按照每单位产出的ATC最低的时候的选择。

#### Economies of scale 规模经济

• Economies of scale – Output↑ LRATC↓
• 规模经济 - 产出↑ 长期平均成本曲线↓
• Constant returns to scale – Output↑ or ↓, LRATC stays the same
• 规模收益不变 - 产出不论上升下降 长期平均成本曲线不变
• Diseconomies of scale – Output↑ LRATC↑
• 规模不经济 - 产出↑ 长期平均成本曲线↑

### Types of profit 利润的类型

#### Explicit costs vs Implicit costs

• Explicit costs 显性成本 需要企业支出货币的投入成本
• Implicit costs 隐性成本 不需要企业支出货币的投入成本（机会成本）
• Total costs 总成本 = Explicit costs + Implicit costs

#### Accounting profit vs Economic profit

• Accounting profit = Total revenue – Explicit costs
• Economic profit = Total revenue – Explicit costs – Implicit costs
• 公司考虑经济利润/损失而不是会计利润

#### Normal profit

Normal profit means zero economic profit.

#### Profit maximization 利润最大化

• When MR > MC, 继续做
• When MR < MC, 少做
• When MR = MC, 保持这样
• MR = MC 的时候是利润最大化的产量

• 在本质上，由于企业的边际成本曲线决定了企业在任何一种价格是愿意供给的物品数量，因此成本曲线也是企业的供给曲线