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Ch. 9 - Differential Equations
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243당신이 사용하는 게 아니라요?교과서 변경
9장, 문제 9.1.52b

52-56. In this section, several models are presented and the solution of the associated differential equation is given. Later in the chapter, we present methods for solving these differential equations.


{Use of Tech} Drug infusion The delivery of a drug (such as an antibiotic) through an intravenous line may be modeled by the differential equation m'(t) + km(t) = I, where m(t) is the mass of the drug in the blood at time t ≥ 0, k is a constant that describes the rate at which the drug is absorbed, and I is the infusion rate.


b. Graph the solution for I = 10 mg/hr and k = 0.05 hr⁻¹.

검증된 단계별 안내
1
Identify the given differential equation: \(m'(t) + k m(t) = I\), where \(I = 10\) mg/hr and \(k = 0.05\) hr\(^{-1}\).
Recognize that this is a first-order linear ordinary differential equation. The standard approach is to find an integrating factor to solve it.
Calculate the integrating factor \(\mu(t) = e^{\int k \, dt} = e^{k t}\), which in this case is \(e^{0.05 t}\).
Multiply both sides of the differential equation by the integrating factor to get \(e^{0.05 t} m'(t) + 0.05 e^{0.05 t} m(t) = 10 e^{0.05 t}\), which simplifies to \(\frac{d}{dt} \left( e^{0.05 t} m(t) \right) = 10 e^{0.05 t}\).
Integrate both sides with respect to \(t\) to find \(e^{0.05 t} m(t) = \int 10 e^{0.05 t} dt + C\), then solve for \(m(t)\) by dividing both sides by \(e^{0.05 t}\). This will give the general solution for \(m(t)\), which you can then graph.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
2m
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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

First-Order Linear Differential Equations

These are differential equations of the form m'(t) + p(t)m(t) = q(t), where the derivative of the function and the function itself appear linearly. The given drug infusion model fits this form, allowing the use of standard methods like integrating factors to find explicit solutions.
추천 영상:
07:39
Classifying Differential Equations

Integrating Factor Method

This technique solves first-order linear differential equations by multiplying both sides by an integrating factor, typically e^(∫p(t)dt), which simplifies the equation into an exact derivative. Applying this method to m'(t) + km(t) = I helps find the general solution for the drug mass over time.
추천 영상:
07:33
Euler's Method

Interpretation and Graphing of Solutions

Once the solution m(t) is found, understanding its behavior over time is crucial. For the drug infusion model, the solution typically approaches a steady-state value, reflecting equilibrium between infusion and absorption. Graphing with given parameters (I = 10, k = 0.05) visualizes this dynamic.
추천 영상:
가이드 코스
06:15
Graphing The Derivative
관련 실천
교과서 질문

Direction field analysis Consider the first-order initial value problem y'(t)=ay+b,y(0)=A for t≥0 where a, b, and A are real numbers.

a. Explain why y=−b/a is an equilibrium solution and corresponds to a horizontal line in the direction field.

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교과서 질문

A bad loan Consider a loan repayment plan described by the initial value problem

B'(t)=0.03B−600,B(0)=40,000,

where the amount borrowed is B(0)=\$40,000, the monthly payments are \$600, and B(t) is the unpaid balance in the loan.

b. What is the most that you can borrow under the terms of this loan without going further into debt each month?

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교과서 질문

{Use of Tech} Chemical rate equations Let y(t) be t he concentration of a substance in a chemical reaction (typical units are moles/liter). The change in the concentration, under appropriate conditions, is modeled by the equation dy/dt=-ky^n for t≥0, where k>0 is a rate constant and the positive integer n is the order of the reaction.

b. Solve the initial value problem for a second-order reaction (n=2) assuming y(0)=y0.

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교과서 질문

Convergence of Euler's method Suppose Euler's method is applied to the initial value problem y′(t) = ay, y(0) = 1, which has the exact solution y(t) = eᵃᵗ. For this exercise, let h denote the time step (rather than Δt). The grid points are then given by tₖ = kh. We let uₖ be the Euler approximation to the exact solution y(tₖ), for k = 0, 1, 2, ...

b. Show by substitution that uₖ = (1 + ah)ᵏ is a solution of the equations in part (a), for k = 0, 1, 2, ...

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교과서 질문

29–32. {Use of Tech} Errors in Euler’s method Consider the following initial value problems.


b. Using the exact solution given, compute the errors in the Euler approximations at t=0.2 and t=0.4.


y′(t) = 2t + 1, y(0) = 0; y(t) = t² + t

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교과서 질문

brOrthogonal trajectories Two curves are orthogonal to each other if their tangent lines are perpendicular at each point of intersection. A family of curves forms orthogonal trajectories with another family of curves if each curve in one family is orthogonal to each curve in the other family. Use the following steps to find the orthogonal trajectories of the family of ellipses 2x² + y² = a²


b. The family of trajectories orthogonal to 2x² + y² = a² satisfies the differential equation dy/dx = y/(2x). Why?

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