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Ch. 9 - First-Order Differential Equations
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Not the one you use?Change textbook
All textbooksHass 15th EditionCh. 9 - First-Order Differential EquationsProblem 9.1.15
Chapter 9, Problem 9.1.15

Using Euler’s Method
In Exercises 15–20, use Euler’s method to calculate the first three approximations to the given initial value problem for the specified increment size. Calculate the exact solution and investigate the accuracy of your approximations. Round your results to four decimal places.


y' = 2y/x, y(1) = -1, dx = 0.5

Verified step by step guidance
1
Identify the differential equation and initial condition: \(y' = \frac{2y}{x}\) with \(y(1) = -1\). The step size is \(\Delta x = 0.5\).
Recall Euler's method formula: \(y_{n+1} = y_n + f(x_n, y_n) \Delta x\), where \(f(x, y) = \frac{2y}{x}\) is the derivative function.
Calculate the first approximation: starting at \(x_0 = 1\), \(y_0 = -1\), compute \(y_1 = y_0 + f(x_0, y_0) \Delta x = y_0 + \frac{2 y_0}{x_0} \times 0.5\).
Calculate the second approximation: update \(x_1 = x_0 + \Delta x\), then compute \(y_2 = y_1 + f(x_1, y_1) \Delta x = y_1 + \frac{2 y_1}{x_1} \times 0.5\).
Calculate the third approximation similarly: update \(x_2 = x_1 + \Delta x\), then compute \(y_3 = y_2 + f(x_2, y_2) \Delta x = y_2 + \frac{2 y_2}{x_2} \times 0.5\). After these, find the exact solution by solving the differential equation and compare the values to assess accuracy.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Euler's Method

Euler's Method is a numerical technique to approximate solutions of first-order differential equations. Starting from an initial point, it uses the slope given by the differential equation to estimate the next value by moving a small step size along the tangent. This iterative process provides approximate values of the solution at discrete points.
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Euler's Method

Initial Value Problem (IVP)

An Initial Value Problem specifies a differential equation along with a starting condition, or initial value, for the unknown function. The solution must satisfy both the differential equation and the initial condition, which anchors the solution curve at a specific point, enabling numerical or analytical methods to find the function.
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Initial Value Problems

Exact Solution and Error Analysis

The exact solution is the precise function satisfying the differential equation and initial condition, often found analytically. Comparing Euler’s approximations to the exact solution helps assess the accuracy of the numerical method. Error analysis involves measuring the difference between approximate and exact values to understand the method’s reliability.
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Determining Error and Relative Error
Related Practice
Textbook Question

Solving Initial Value Problems

Solve the initial value problems in Exercises 15–20.

dy/dt + 2y = 3, y(0) = 1

Textbook Question

Solve the Bernoulli equations in Exercises 29–32.


y' - y = xy²

Textbook Question

What integral equation is equivalent to the initial value problem y' = f(x), y(x₀) = y₀?

Textbook Question

Solving Initial Value Problems

Solve the initial value problems in Exercises 15–20.


dy/dx + xy = x, y(0) = -6

Textbook Question

Using Euler’s Method

In Exercises 15–20, use Euler’s method to calculate the first three approximations to the given initial value problem for the specified increment size. Calculate the exact solution and investigate the accuracy of your approximations. Round your results to four decimal places.


y' = y²(1+2x), (y-1) = 1, dx = 0.5

Textbook Question

First-Order Linear Equations

Solve the differential equations in Exercises 1–14.


e²ˣy' + 2e²ˣ y = 2x