Questions: Consider the following matrices.
A = [ [3, -1, -1], [1, -3, 3] ]
x = [ [x1], [x2], [x3] ]
0 = [ [0], [0] ]
Solve the matrix equation Ax=0. (If there is no solution, enter No Solution. If the system has an infinite number of solutions, express x1, x2, and x3 in terms of the parameter t.) (x1, x2, x3) = ( )
Transcript text: Consider the following matrices.
\[
\begin{aligned}
A & =\left[\begin{array}{ccc}
3 & -1 & -1 \\
1 & -3 & 3
\end{array}\right] \\
\vec{x} & =\left[\begin{array}{l}
x_{1} \\
x_{2} \\
x_{3}
\end{array}\right] \\
\overrightarrow{0} & =\left[\begin{array}{l}
0 \\
0
\end{array}\right]
\end{aligned}
\]
Solve the matrix equation $A \vec{x}=\overrightarrow{0}$. (If there is no solution, enter No Solution. If the system has an infinite number of solutions, express $x_{1}, x_{2}$, and $x_{3}$ in terms of the parameter $t$.) $\left(x_{1}, x_{2}, x_{3}\right)=(\square$ $\square$ )
Solution
Solution Steps
To solve the matrix equation \( A \vec{x} = \overrightarrow{0} \), we need to find the null space of matrix \( A \). This involves performing row reduction (Gaussian elimination) on the augmented matrix \([A | \overrightarrow{0}]\) to find the solutions for \(\vec{x}\). If the system has free variables, it indicates an infinite number of solutions, which can be expressed in terms of a parameter.
Step 1: Set Up the Matrix Equation
We are given the matrix equation \( A \vec{x} = \overrightarrow{0} \), where
\[
A = \begin{bmatrix} 3 & -1 & -1 \\ 1 & -3 & 3 \end{bmatrix}
\]
and
\[
\vec{x} = \begin{bmatrix} x_1 \\ x_2 \\ x_3 \end{bmatrix}
\]
We need to find the solutions for \(\vec{x}\) that satisfy this equation.
Step 2: Find the Null Space of Matrix \( A \)
To solve \( A \vec{x} = \overrightarrow{0} \), we find the null space of matrix \( A \). The null space consists of all vectors \(\vec{x}\) such that \( A \vec{x} = \overrightarrow{0} \).
Step 3: Perform Row Reduction
Perform row reduction on the matrix \( A \) to find its null space. The row-reduced form of \( A \) reveals that there is one free variable, indicating an infinite number of solutions.
Step 4: Express Solutions in Terms of a Parameter
The null space of \( A \) is spanned by the vector
\[
\begin{bmatrix} \frac{3}{4} \\ \frac{5}{4} \\ 1 \end{bmatrix}
\]
This means that the solutions can be expressed in terms of a parameter \( t \) as follows:
\[
\vec{x} = t \begin{bmatrix} \frac{3}{4} \\ \frac{5}{4} \\ 1 \end{bmatrix}
\]
where \( t \) is any real number.
Final Answer
The solutions to the matrix equation \( A \vec{x} = \overrightarrow{0} \) are given by:
\[
(x_1, x_2, x_3) = \left( \frac{3}{4}t, \frac{5}{4}t, t \right)
\]
\[
\boxed{(x_1, x_2, x_3) = \left( \frac{3}{4}t, \frac{5}{4}t, t \right)}
\]