Chapter 10: Problem 7
\(y^{\prime}+y^{2}=0\).
Short Answer
Expert verified
The solution is \( y = \frac{1}{x + C} \).
Step by step solution
01
Identify the Type of Differential Equation
The given equation is \( y' + y^2 = 0 \). This is a first-order ordinary differential equation and is separable, meaning it can be rewritten as separate functions of \( y \) and \( x \).
02
Rearrange the Equation for Separation
Rearrange the equation to explicitly separate the variables: \( y' = -y^2 \). This allows us to separate \( y \) on one side and \( x \) on the other.
03
Separate Variables
Rewrite \( y' = \frac{dy}{dx} \) and separate the variables: \( \frac{dy}{y^2} = -dx \).
04
Integrate Both Sides
Integrate both sides of the separated equation: \( \int \frac{dy}{y^2} = \int -dx \). This gives \( -\frac{1}{y} = -x + C_1 \), where \( C_1 \) is the constant of integration.
05
Solve for y
Rearrange the equation to solve for \( y \): \( \frac{1}{y} = x + C_1 \), therefore, \( y = \frac{1}{x + C_1} \). This is the general solution of the differential equation.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
First-order Ordinary Differential Equations
First-order ordinary differential equations are fundamental in calculus and mathematics. These equations involve derivatives of a function with respect to one variable and are of the first order since they only contain first derivatives. In the equation given, \( y'+y^2=0 \), \( y' \) represents the derivative of \( y \) with respect to \( x \).
Understanding these types of equations is crucial, as they often model important real-world phenomena like population growth, heat transfer, and financial systems.
Understanding these types of equations is crucial, as they often model important real-world phenomena like population growth, heat transfer, and financial systems.
- These equations are represented in the format \( \, f(x,y,y') = 0 \, \), focusing on the relationship between the function and its derivative.
- The main challenge is to find the function \( y \, \) that satisfies such an equation.
- These equations could be linear or nonlinear, as in our example, because of the \( y^2 \, \) term.
Variable Separation
A powerful technique for solving first-order differential equations is variable separation. Here, you rewrite the equation in a way that allows you to separate and relocate variables on different sides of the equation.
In the example equation, \( y' + y^2 = 0 \), the goal is to express it so that all \( y \, \) terms are on one side and all \( x \, \) terms are on the other. We achieve this by:
In the example equation, \( y' + y^2 = 0 \), the goal is to express it so that all \( y \, \) terms are on one side and all \( x \, \) terms are on the other. We achieve this by:
- Rewriting \( y' \) as \( \frac{dy}{dx} \) to better expose the differential nature of the terms.
- Then, rearranging to yield \( \frac{dy}{y^2} = -dx \), making it easier to integrate both sides separately.
Integration Techniques
Once variables are separated, integration becomes the tool to solve for the function. Integration involves finding a function whose derivative matches given terms. For the equation from the example, \( \frac{dy}{y^2} = -dx \), you need to integrate each side.
- The left side, \( \int \frac{dy}{y^2} \), uses the power rule, resulting in the integration of \( y^{-2} \, \).
- The right side, \( \int -dx \), is elementary and results in \( -x \, \).
General Solution of Differential Equations
The ultimate objective when solving differential equations is obtaining the general solution. This solution encapsulates all possible specific solutions of a differential equation using arbitrary constants.
From our integrated equation, \( -\frac{1}{y} = -x + C_1 \), rearranging terms helps isolate \( y \). By doing algebraic manipulation, we find that \( y = \frac{1}{x + C_1} \).
From our integrated equation, \( -\frac{1}{y} = -x + C_1 \), rearranging terms helps isolate \( y \). By doing algebraic manipulation, we find that \( y = \frac{1}{x + C_1} \).
- The general solution shows how \( y \, \) depends on \( x \, \) and includes the constant \( C_1 \), signifying any initial condition can determine a particular solution.
- This constant stems from the indefinite integral and represents an integration constant unique to each problem setup.
- General solutions offer the flexibility needed to adapt the solution to initial values or boundary conditions in real-life scenarios.