Chapter 13: Problem 18
Find all of the solutions of the systems. $$ \left(\begin{array}{rr} 1 & 4 \\ -1 & 1 \end{array}\right)\left(\begin{array}{l} x \\ y \end{array}\right)=0 $$
Short Answer
Expert verified
The solution is \( x = 0 \) and \( y = 0 \).
Step by step solution
01
Set Up the System of Equations
The given matrix equation can be expanded into two separate linear equations. From the matrix multiplication, \( \begin{pmatrix} 1 & 4 \ -1 & 1 \end{pmatrix} \begin{pmatrix} x \ y \end{pmatrix} = \begin{pmatrix} 0 \ 0 \end{pmatrix} \), we derive the following system:1. \( 1x + 4y = 0 \).2. \( -1x + 1y = 0 \).
02
Solve the First Equation
From the first equation, \( x + 4y = 0 \), solve for \( x \). This gives:\[ x = -4y \].
03
Solve the Second Equation using the First Equation's Solution
Substitute \( x = -4y \) from Step 2 into the second equation \( -x + y = 0 \):\[ -(-4y) + y = 0 \].This simplifies to \( 4y + y = 0 \), which further simplifies to \( 5y = 0 \).
04
Solve for \( y \)
From \( 5y = 0 \), we find that \( y = 0 \).
05
Determine \( x \) Using the Value of \( y \)
Substitute the value of \( y = 0 \) back into the equation \( x = -4y \):\[ x = -4(0) = 0 \].
06
Conclusion of Solutions
The solution to the system is \( x = 0 \) and \( y = 0 \), or simply \( \begin{pmatrix} 0 \ 0 \end{pmatrix} \). This means the only solution is the trivial solution where both variables are zero.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Matrix Equations
Matrix equations are a key part of linear algebra. They involve the multiplication of matrices and vectors to find solutions. In simple terms:
- The matrix provides coefficients for variables.
- The vector represents the variables.
- Multiplying them gives the result vector.
- Extract linear equations by examining each row of the matrix.
- This converts the matrix equation into individual linear equations for the variables \( x \) and \( y \).
Linear Systems
A linear system involves two or more linear equations that are connected by shared variables. In the context of the exercise, you are dealing with the linear system resulting from:\[ \begin{aligned} &1x + 4y = 0 \ &-1x + 1y = 0 \end{aligned} \]To solve a linear system, especially when tackling multiple equations, the goal is to find values for the variables that satisfy all equations simultaneously. Here’s how you can approach solving a linear system:
- Substitute: Isolate a variable in one equation, then substitute into the other.
- Elimination: Add or subtract equations to eliminate a variable, simplifying the system.
- Check: Always verify solutions by substituting back into the original equations to ensure all are satisfied.
Trivial Solution
In linear algebra, a trivial solution occurs when the only solution to the system is for all variables to be zero. For the provided matrix equation, we discovered that:\[ x = 0 \quad \text{and} \quad y = 0 \]This is a classic case of a trivial solution. Here are some characteristics of trivial solutions:
- They denote the simplest solution.
- Such a result in a homogeneous system (a system where all constants are zero) is common.
- Finding only a trivial solution usually implies the system does not describe an enriched geometry like an intersection point outside the origin.