/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 42 Explain what is wrong with the s... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Explain what is wrong with the statement. The differential equation \(d P / d t=0.08 P-0.0032 P^{2}\) has one equilibrium solution, at \(P=25\)

Short Answer

Expert verified
The differential equation has two equilibrium solutions: \( P = 0 \) and \( P = 25 \).

Step by step solution

01

Understanding the Differential Equation

The differential equation given is \( \frac{dP}{dt} = 0.08P - 0.0032P^2 \). This describes the rate of change of \( P \) with respect to \( t \). We're interested in finding equilibrium solutions, where \( \frac{dP}{dt} = 0 \), which means \( P \) is constant over time.
02

Setting the Rate of Change to Zero

Set the rate of change equal to zero to find the equilibrium points: \[0 = 0.08P - 0.0032P^2\]This simplifies to solving the quadratic equation \( 0.0032P^2 - 0.08P = 0 \).
03

Factoring the Equation

Factor the equation: \[P(0.0032P - 0.08) = 0\]This gives us the potential solutions \( P = 0 \) or \( 0.0032P - 0.08 = 0 \).
04

Solving the Linear Part

Solve the equation \( 0.0032P - 0.08 = 0 \): \[0.0032P = 0.08\]Divide both sides by 0.0032 to find \( P \): \[P = \frac{0.08}{0.0032} = 25\]Thus, the equilibrium solutions are \( P = 0 \) and \( P = 25 \).
05

Determining the Mistake

The statement claims there is only one equilibrium solution at \( P = 25 \), but calculations show two equilibrium solutions: \( P = 0 \) and \( P = 25 \). The statement is incorrect because it overlooks the solution at \( P = 0 \).

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Equilibrium Solutions in Differential Equations
In the context of differential equations, equilibrium solutions are crucial as they offer insights into the system's behavior at steady-state conditions, where variables do not change over time. For a differential equation of the form \( \frac{dP}{dt} = f(P) \), an equilibrium solution occurs when \( f(P) = 0 \). This indicates that the derivative of \( P \) with respect to time, \( t \), is zero, meaning there's no change or movement from that point.

Finding equilibrium points typically involves setting the given differential equation to zero and solving for the variable, as these values do not adjust over time. Identifying these solutions is essential in understanding the stability and the long-term behavior of the system being modeled.

In our example, the given differential equation is \( \frac{dP}{dt} = 0.08P - 0.0032P^2 \). Setting this to zero finds where \( P \) remains constant, leading to equilibrium solutions.
Understanding the Rate of Change
The rate of change in mathematics and physics describes how a quantity varies with respect to another. In the context of differential equations, it often refers to how the dependent variable changes with time. The expression \( \frac{dP}{dt} \) indicates how \( P \) changes as time \( t \) progresses.

In our scenario, \( \frac{dP}{dt} = 0.08P - 0.0032P^2 \) gives the rate of change of \( P \).
  • The term \( 0.08P \) represents a proportional increase in \( P \), akin to growth or gain.
  • On the other hand, \( -0.0032P^2 \) relates to a decrease, like a reduction in speed, potentially due to limiting factors or constraints.
Thus, solving the equation helps determine how various values of \( P \) influence the change's direction and magnitude. Identifying where \( \frac{dP}{dt} = 0 \) is essential to locating equilibrium states.
Solving the Quadratic Equation
A quadratic equation is any equation that can be structured in the form \( ax^2 + bx + c = 0 \), where \( a \), \( b \), and \( c \) are constants, and \( a eq 0 \). Solving these equations reveals the roots or solutions, which are the values of the unknown variable that satisfy the equation.

In our example, once the rate of change is set to zero, we're faced with a simple quadratic equation:\[ 0.0032P^2 - 0.08P = 0 \]This form highlights that there might be more than one solution.

Approaching this task involves either factoring or using the quadratic formula. Each solution corresponds to a possible equilibrium point in our differential equation's context. Correctly simplifying and solving these equations is pivotal in determining all valid equilibrium solutions.
Factoring Equations Intuitively
Factoring equations is a process of breaking down an equation into simpler, multiplied expressions. This is particularly useful for quadratic equations like \( ax^2 + bx = 0 \), which can often be solved by factoring.

For our differential equation, where:\[ 0.0032P^2 - 0.08P = 0 \]factoring helps to extract the solutions efficiently. The expression can be factored as:\[ P(0.0032P - 0.08) = 0 \]This approach elegantly yields potential values for \( P \) by examining each factor.

The separation gives two straightforward scenarios:
  • \( P = 0 \) makes the equation true.
  • \( 0.0032P - 0.08 = 0 \) is then solved to find \( P = 25 \).
Thus, factoring not only simplifies the computation but also verifies multiple equilibrium solutions have been properly identified and considered.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

The total number of people infected with a virus often grows like a logistic curve. Suppose that time, \(t,\) is in weeks and that 10 people originally have the virus. In the early stages, the number of people infected is increasing exponentially with \(k=1.78 .\) In the long run, 5000 people are infected. (a) Find a logistic function to model the number of people infected. (b) Sketch a graph of your answer to part (a). (c) Use your graph to estimate the length of time until the rate at which people are becoming infected starts to decrease. What is the vertical coordinate at this point?

Decide whether the statement is true or false. Assume that \(y=f(x)\) is a solution to the equation \(d y / d x=2 x-y .\) Justify your answer. If \(f(a)=b,\) the slope of the graph of \(f\) at \((a, b)\) is \(2 a-b\)

Sketch solution curves with a variety of initial values for the differential equations. You do not need to find an equation for the solution. \(\frac{d y}{d t}=\alpha-y,\) where \(\alpha\) is a positive constant.

Let \(L,\) a constant, be the number of people who would like to see a newly released movie, and let \(N(t)\) be the number of people who have seen it during the first \(t\) days since its release. The rate that people first go see the movie, \(d N / d t\) (in people/day), is proportional to the number of people who would like to see it but haven't yet. Write and solve a differential equation describing \(d N / d t\) where \(t\) is the number of days since the movie's release. Your solution will involve \(L\) and a constant of proportionality, \(k\).

Decide whether the statement is true or false. Assume that \(y=f(x)\) is a solution to the equation \(d y / d x=2 x-y .\) Justify your answer. The graph of \(f\) is decreasing whenever it lies above the line \(y=2 x\) and is increasing whenever it lies below the line \(y=2 x\)

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.