Chapter 4: Problem 213
Write the following first-order differential equations in standard form. $$ y^{\prime}=x^{3} y+\sin x $$
Short Answer
Expert verified
The standard form is \( y' - x^3 y = \sin x \).
Step by step solution
01
Identify the Equation
The given differential equation is \( y' = x^3 y + \sin x \). Our goal is to write this equation in standard form.
02
Recall Standard Form of a First-Order DE
For a first-order linear differential equation, the standard form is \( y' + P(x)y = Q(x) \), where \( P(x) \) and \( Q(x) \) are functions of \( x \).
03
Rearrange to Match Standard Form
In the equation \( y' = x^3 y + \sin x \), rearrange it to match the form \( y' + P(x)y = Q(x) \). Move the \( x^3 y \) term to the left-hand side: \( y' - x^3 y = \sin x \).
04
Identify the Standard Form Components
Now that the equation \( y' - x^3 y = \sin x \) is in standard form, identify \( P(x) \) and \( Q(x) \). Here, \( P(x) = -x^3 \) and \( Q(x) = \sin x \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Standard Form
The standard form of a first-order differential equation is essential for solving and analyzing these equations. In mathematics, a first-order linear differential equation can be expressed as \[ y' + P(x)y = Q(x) \]. This form allows us to see the structure of the equation more clearly. Here, \( y' \) represents the derivative of \( y \) with respect to \( x \).
- \( P(x) \) is known as the coefficient of \( y \), which is a function of \( x \).
- \( Q(x) \) is the function on the right-hand side that does not contain the dependent variable \( y \).
Linear Differential Equation
Linear differential equations, as the name suggests, are equations that involve a linear combination of a function and its derivatives. They play a crucial role in both mathematics and physics. For first-order linear differential equations, the general form is \[ y' + P(x)y = Q(x) \].They are considered 'linear' because:
- The dependent variable \( y \) and its derivative \( y' \) appear to the first power, and are not multiplied together.
- There are no products of the dependent variable and its powers or products of the derivative with itself.
Rearrange Equations
When dealing with first-order differential equations, rearranging terms to fit the standard form is a key step. Let's look at our original equation: \[ y' = x^3 y + \sin x \].To write this in standard form, we need to adjust the equation to match the structure \[ y' + P(x)y = Q(x) \].Here's how we do it:
- Move all terms involving the dependent variable \( y \) to one side of the equation.
- In our case, subtract \( x^3 y \) from both sides to isolate the terms involving \( y \): \[ y' - x^3 y = \sin x \].
Identify Components
Identifying the components of a first-order differential equation, once it is in standard form, is fundamental for solving it correctly. In our standard form\[ y' + P(x)y = Q(x) \],the terms \( P(x) \) and \( Q(x) \) must be clearly understood:
- \( P(x) \) is the function that multiplies the dependent variable \( y \). In the equation: \[ y' - x^3 y = \sin x \], \( P(x) \) is identified as \(-x^3 \).
- \( Q(x) \) stands for the part of the equation that does not involve \( y \). Here, it is \( \sin x \).