Chapter 5: Problem 16
For each demand function, find \(E(p)\) and determine if demand is elastic or inelastic (or neither) at the indicated price. $$ q=\left(77 / p^{2}\right)+3, p=1 $$
Short Answer
Expert verified
The price elasticity of demand is \( -1.925 \) and the demand is elastic at the price \( p = 1 \).
Step by step solution
01
Find the derivative of the demand function with respect to price
The demand function is given as \( q = \left(\frac{77}{p^2}\right) + 3 \). To find the price elasticity of demand, first find the derivative of the demand function with respect to price, \( p \). The derivative \( \frac{dq}{dp} \) can be found using the power rule and chain rule of differentiation.
02
Apply the power rule
For the term \( \left(\frac{77}{p^2}\right) \), rewrites as \( 77 p^{-2} \). Its derivative with respect to \( p \) is \( -154 p^{-3} \). The term 3 is a constant, so its derivative is 0. Hence, \( \frac{dq}{dp} = -154 p^{-3} \).
03
Use the formula for price elasticity of demand
The formula for price elasticity of demand is \( E(p) = \left( \frac{p}{q} \right) \cdot \left( \frac{dq}{dp} \right) \). We already have \( \frac{dq}{dp} = -154 p^{-3} \). Now, substitute it along with \( q \) and \( p \) into the elasticity formula.
04
Substitute \( p = 1 \)
Given that \( p = 1 \), first find \( q \). Substituting \( p = 1 \) into the demand function, \( q = \left( \frac{77}{1^2} \right) + 3 = 77 + 3 = 80 \).
05
Calculate \( E(1) \)
Substitute \( p = 1 \), \( q = 80 \), and \( \frac{dq}{dp} = -154 \) into the elasticity formula: \[ E(1) = \left( \frac{1}{80} \right) \cdot (-154) = -\frac{154}{80} = -1.925 \]
06
Determine elasticity type
Price elasticity of demand \( E(p) = -1.925 \). Since \( |E(p)| > 1 \), the demand is elastic at the price \( p = 1 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Differentiation
Differentiation is a mathematical process where we find the rate at which a function changes. It is essential when working with demand functions, as it helps to determine how the quantity demanded changes with a change in price.
In this exercise, we differentiate the demand function with respect to price to find the elasticity. For a function like this: \( q = \frac{77}{p^2} + 3 \), we apply rules of differentiation.
Remember that for a term like \( \frac{77}{p^2} \), you can rewrite it as \( 77p^{-2} \). Differentiating this term involves using the power rule.
In this exercise, we differentiate the demand function with respect to price to find the elasticity. For a function like this: \( q = \frac{77}{p^2} + 3 \), we apply rules of differentiation.
Remember that for a term like \( \frac{77}{p^2} \), you can rewrite it as \( 77p^{-2} \). Differentiating this term involves using the power rule.
Demand Function
A demand function describes the relationship between the quantity of a good demanded and its price. It is typically written as \( q = f(p) \), where \( q \) is quantity and \( p \) is price.
Understanding the demand function is crucial in economics because it helps businesses set prices optimally. In our exercise, the function given is \( q = \frac{77}{p^2} + 3 \). This function indicates that as the price \( p \) changes, the quantity demanded \( q \) also changes.
Understanding the demand function is crucial in economics because it helps businesses set prices optimally. In our exercise, the function given is \( q = \frac{77}{p^2} + 3 \). This function indicates that as the price \( p \) changes, the quantity demanded \( q \) also changes.
Elasticity Calculation
Price elasticity of demand measures how responsive the quantity demanded is to a change in price. It is calculated using this formula: \[ E(p) = \frac{p}{q} \times \frac{dq}{dp} \].
Let's break it down:
Let's break it down:
- Find \( \frac{dq}{dp} \), the derivative of the demand function with respect to price.
- Substitute the price \( p \) and quantity \( q \) values into the formula.
- The result tells whether the demand is elastic (\( |E(p)| > 1 \)), inelastic (\( |E(p)| < 1 \)), or unitary elastic (\( |E(p)| = 1 \)).
- In our example: \( E(p) = -1.925 \), the demand is elastic since its absolute value is greater than 1.
Power Rule
The power rule is a fundamental tool in differentiation. It states that if you have a function of the form \( f(x) = x^n \), its derivative is \( f'(x) = nx^{n-1} \).
When using the power rule on our demand function term \( 77p^{-2} \), we get:
When using the power rule on our demand function term \( 77p^{-2} \), we get:
- \( f(p) = 77p^{-2} \)
- Differentiating: \( f'(p) = -154p^{-3} \)