Chapter 2: Problem 2
Solve the given differential equation by separation of variables. $$ \frac{d y}{d x}=(x+1)^{2} $$
Short Answer
Expert verified
The solution is \( y = \frac{x^3}{3} + x^2 + x + C \).
Step by step solution
01
Rewrite the differential equation
The differential equation given is \( \frac{dy}{dx} = (x+1)^2 \). To solve it using separation of variables, rewrite the equation to separate \( y \) and \( x \) as follows: \( dy = (x+1)^2 dx \).
02
Integrate both sides
Now integrate both sides. The left side integrates to \( \int dy = y \), and the right side integrates as \( \int (x+1)^2 dx \).
03
Solve the integral on the right side
Find the antiderivative of \( (x+1)^2 \). Expand the expression: \( (x+1)^2 = x^2 + 2x + 1 \). Integrate each term separately: \( \int x^2 \, dx = \frac{x^3}{3}, \int 2x \, dx = x^2, \int 1 \, dx = x \). Thus, \( \int (x+1)^2 \, dx = \frac{x^3}{3} + x^2 + x + C \), where \( C \) is the constant of integration.
04
Write the general solution
Combine the results from previous steps to write the general solution. On the left side, we have \( y = \frac{x^3}{3} + x^2 + x + C \). Thus, the solution to the differential equation is \( y = \frac{x^3}{3} + x^2 + x + C \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Differential Equations
Differential equations are mathematical equations that relate a function with its derivatives. They're a fundamental part of calculus and used to describe various physical phenomena such as motion, heat, and fluid dynamics. In our exercise, the differential equation given is \( \frac{dy}{dx} = (x+1)^2 \). This is a first-order ordinary differential equation, meaning it involves only the first derivative of the function \( y \). It describes a relationship between \( y \), its rate of change with respect to \( x \), and the expression \((x+1)^2\). By solving the differential equation, we find a function \( y \) that satisfies this relationship. The main goal is to determine \( y \) as a function of \( x \). This demands techniques such as separation of variables which we'll explore further.
Integration
Integration is the process of finding the integral of a function, which is essentially the opposite of differentiation. In the context of solving differential equations, integration is used to find functions whose derivative matches a given equation. In our exercise, after rewriting the differential equation as \( dy = (x+1)^2 dx \), we integrated both sides to proceed with finding \( y \).
- Left Side: \( \int dy = y \)
- Right Side: \( \int (x+1)^2 dx \)
Antiderivative
The antiderivative, also known as the indefinite integral, represents the family of functions that a given function may have been derived from. During the integration process in the step-by-step solution, we focused on finding the antiderivative of \( (x+1)^2 \). Once we expand \( (x+1)^2 \) to \( x^2 + 2x + 1 \), each term's antiderivative is calculated separately:
- \( \int x^2 \, dx = \frac{x^3}{3} \)
- \( \int 2x \, dx = x^2 \)
- \( \int 1 \, dx = x \)
Constant of Integration
The constant of integration, represented typically as \( C \), emerges when computing an indefinite integral. It acknowledges that there are infinitely many functions which could lead to the same derivative since adding any constant to a function doesn't affect its derivative. In our solution, after integrating \( (x+1)^2 \), the result included \( C \) in \( \frac{x^3}{3} + x^2 + x + C \). This constant embodies all possible vertical shifts of our antiderivative, making it a general solution rather than a specific one. Specific solutions can often be determined if initial conditions are provided, fixing the value of \( C \). In practice, finding \( C \) allows for more precise modeling of real-world scenarios by matching specific or initial conditions to have a complete function that fits the given context.