Chapter 12: Problem 45
Solve the vector initial-value problem for \(\mathbf{y}(t)\) by integrating and using the initial conditions to find the constants of integration. $$ \mathbf{y}^{\prime}(t)=2 t \mathbf{i}+3 t^{2} \mathbf{j}, \mathbf{y}(0)=\mathbf{i}-\mathbf{j} $$
Short Answer
Step by step solution
Identify the given vector differential equation
Integrate the vector component-wise
Apply initial conditions to solve for constants
Write the final vector function
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Initial-Value Problem
- The differential equation is \( \mathbf{y}'(t) = 2t \mathbf{i} + 3t^2 \mathbf{j} \).
- The initial condition, provided as \( \mathbf{y}(0) = \mathbf{i} - \mathbf{j} \), is crucial. It tells us the specific value of the function at \( t = 0 \).
The objective is to determine the exact form of \( \mathbf{y}(t) \) that meets both the differential equation and initial condition. It's like solving a puzzle. By using the given initial condition, we can solve for any constants after integrating.
Indeed, this step ensures that the solution aligns with the pre-defined start settings of the problem. This alignment is why we call it an 'initial'-value problem.
Vector Integration
- For the \( \mathbf{i} \)-component: Integrate \( 2t \) with respect to \( t \), leading to \( \int 2t \, dt = t^2 + C_1 \).
- For the \( \mathbf{j} \)-component: Integrate \( 3t^2 \) with respect to \( t \), resulting in \( \int 3t^2 \, dt = t^3 + C_2 \).
The constants \( C_1 \) and \( C_2 \) represent integration constants that we need to determine. Ensuring these components align with the initial conditions will give us the correct form of \( \mathbf{y}(t) \). Vector integration is thus a systematic approach to unravel each part of the vector function while accommodating the initial puzzle pieces.
Differential Equations
- The vectors \( \mathbf{i} \) and \( \mathbf{j} \) give us direction, while the expressions \( 2t \) and \( 3t^2 \) provide the rate of change.
- Solving these involves finding a function \( \mathbf{y}(t) \) that returns the initial state \( \mathbf{y}(0) = \mathbf{i} - \mathbf{j} \) when substituted back into the equation.
The integration generates a general solution, but the initial conditions guide us to a specific solution, ensuring the characteristics of both time and starting point are honored. By solving the intricacies of differential equations, we piece together how processes and functions behave over time.