Chapter 5: Problem 44
BUSINESS: Cost A company's marginal cost function is \(M C=21 x^{4 / 3}-6 x^{1 / 2}+50\), where \(x\) is the number of units, and fixed costs are \(\$ 3000\). Find the cost function.
Short Answer
Expert verified
The cost function is \( C(x) = 9x^{7/3} - 4x^{3/2} + 50x + 3000 \).
Step by step solution
01
Understanding Marginal Cost
The marginal cost (MC) function, denoted by \( MC = 21x^{4/3} - 6x^{1/2} + 50 \), represents the rate of change of the total cost with respect to the number of units, \( x \). To find the cost function, you will need to integrate the marginal cost function with respect to \( x \).
02
Integrate the Marginal Cost Function
To find the cost function from the marginal cost function, integrate each term of \( MC \) with respect to \( x \):\[\int MC \, dx = \int (21x^{4/3} - 6x^{1/2} + 50) \, dx\]This gives:\[\int 21x^{4/3} \, dx = \frac{21}{(4/3)+1} x^{(4/3)+1} = \frac{21}{7/3} x^{7/3} = 9x^{7/3}\]\[\int -6x^{1/2} \, dx = \frac{-6}{(1/2)+1} x^{(1/2)+1} = \frac{-6}{3/2} x^{3/2} = -4x^{3/2}\]\[\int 50 \, dx = 50x\]
03
Construct the General Cost Function
Combine the integrated terms to form the general cost function, \( C(x) \):\[ C(x) = 9x^{7/3} - 4x^{3/2} + 50x + C_0 \]where \( C_0 \) is the constant of integration determined by the fixed costs.
04
Determine the Constant of Integration
Use the fixed costs to determine \( C_0 \). Given that the fixed costs are \$3000, when \( x = 0 \), the cost function is equal to these fixed costs:\[ C(0) = 9(0)^{7/3} - 4(0)^{3/2} + 50(0) + C_0 = 3000 \]Thus, \( C_0 = 3000 \).
05
Write the Complete Cost Function
Substitute \( C_0 \) back into the cost function:\[ C(x) = 9x^{7/3} - 4x^{3/2} + 50x + 3000 \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Marginal Cost
The marginal cost is a fundamental concept in economics, representing the cost of producing one additional unit of a good. It's vital for businesses to understand how costs change with varying levels of production.
- The marginal cost function in our problem is given by: \( MC = 21x^{4/3} - 6x^{1/2} + 50 \).
- This function shows the rate at which the total cost changes as more units are produced.
- Knowing the marginal cost helps businesses set optimal production levels to maximize profits.
Integration
Integration is a mathematical process used to find the antiderivative or the general form of a function. In the context of finding a cost function, integration is used to determine the total cost from the marginal cost function.
- To achieve this, we integrate the marginal cost function \( MC = 21x^{4/3} - 6x^{1/2} + 50 \) with respect to \( x \). This provides us the total cost function \( C(x) \).
- The integration of each term separately yields:\[\int 21x^{4/3} \, dx = 9x^{7/3}, \\int -6x^{1/2} \, dx = -4x^{3/2}, \\int 50 \, dx = 50x\]
Fixed Costs
Fixed costs are expenses that do not change with the level of goods or services produced. These costs are incurred even when production is zero.
- Examples include rent, salaries, and insurance.
- In our problem, the fixed costs are given as \$3000.
- These fixed costs help determine the constant of integration \( C_0 \) when integrating the marginal cost function.
- This constant \( C_0 \) ensures that the cost function incorporates all components of production cost, both variable and fixed.
Calculus in Business
Calculus is a powerful mathematical tool in business, especially in analyzing changes over time. It helps businesses determine cost efficiency, profit, and optimal production levels.
- Through calculus, businesses can find the cost function by integrating the marginal cost, as demonstrated here.
- It helps in identifying how costs evolve as production scales, providing strategic insights into production planning.
- Optimization techniques in calculus aid in maximizing profits by finding the production level where costs are minimized.
- Knowledge of differential calculus enables businesses to determine the break-even points and other key metrics essential for financial health.