Math Problem Statement

Let A be a 3x3 matrix such that Nul(A) = Span([[-1], [-3], [3]], [[-2], [2], [2]]). Assume that the vector v = [-2, 1, -3] is a solution of the matrix equation Ax = [44, -44, 88]. Find three vectors v1, v2, v3, different from v, which are also solutions of this equation.

Solution

The problem asks for three vectors v1,v2,v3\mathbf{v}_1, \mathbf{v}_2, \mathbf{v}_3, distinct from v=[213]\mathbf{v} = \begin{bmatrix} -2 \\ 1 \\ -3 \end{bmatrix}, that also solve the matrix equation Ax=[444488]\mathbf{A} \mathbf{x} = \begin{bmatrix} 44 \\ -44 \\ 88 \end{bmatrix}. Given the null space (kernel) of the matrix A\mathbf{A}, Nul(A)\text{Nul}(\mathbf{A}), is spanned by two vectors:

Nul(A)=Span([133],[222])\text{Nul}(\mathbf{A}) = \text{Span} \left( \begin{bmatrix} -1 \\ -3 \\ 3 \end{bmatrix}, \begin{bmatrix} -2 \\ 2 \\ 2 \end{bmatrix} \right)

This suggests that any solution to Ax=[444488]\mathbf{A} \mathbf{x} = \begin{bmatrix} 44 \\ -44 \\ 88 \end{bmatrix} is of the form:

x=v+c1[133]+c2[222]\mathbf{x} = \mathbf{v} + c_1 \begin{bmatrix} -1 \\ -3 \\ 3 \end{bmatrix} + c_2 \begin{bmatrix} -2 \\ 2 \\ 2 \end{bmatrix}

where v=[213]\mathbf{v} = \begin{bmatrix} -2 \\ 1 \\ -3 \end{bmatrix}, and c1c_1 and c2c_2 are arbitrary constants.

To find three distinct vectors v1,v2,v3\mathbf{v}_1, \mathbf{v}_2, \mathbf{v}_3, we need to choose different values of c1c_1 and c2c_2. Let's compute:

  1. For v1\mathbf{v}_1, set c1=1c_1 = 1 and c2=0c_2 = 0:

v1=v+[133]=[213]+[133]=[320]\mathbf{v}_1 = \mathbf{v} + \begin{bmatrix} -1 \\ -3 \\ 3 \end{bmatrix} = \begin{bmatrix} -2 \\ 1 \\ -3 \end{bmatrix} + \begin{bmatrix} -1 \\ -3 \\ 3 \end{bmatrix} = \begin{bmatrix} -3 \\ -2 \\ 0 \end{bmatrix}

  1. For v2\mathbf{v}_2, set c1=0c_1 = 0 and c2=1c_2 = 1:

v2=v+[222]=[213]+[222]=[431]\mathbf{v}_2 = \mathbf{v} + \begin{bmatrix} -2 \\ 2 \\ 2 \end{bmatrix} = \begin{bmatrix} -2 \\ 1 \\ -3 \end{bmatrix} + \begin{bmatrix} -2 \\ 2 \\ 2 \end{bmatrix} = \begin{bmatrix} -4 \\ 3 \\ -1 \end{bmatrix}

  1. For v3\mathbf{v}_3, set c1=1c_1 = 1 and c2=1c_2 = 1:

v3=v+[133]+[222]=[213]+[315]=[502]\mathbf{v}_3 = \mathbf{v} + \begin{bmatrix} -1 \\ -3 \\ 3 \end{bmatrix} + \begin{bmatrix} -2 \\ 2 \\ 2 \end{bmatrix} = \begin{bmatrix} -2 \\ 1 \\ -3 \end{bmatrix} + \begin{bmatrix} -3 \\ -1 \\ 5 \end{bmatrix} = \begin{bmatrix} -5 \\ 0 \\ 2 \end{bmatrix}

Thus, the solutions are:

v1=[320],v2=[431],v3=[502]\mathbf{v}_1 = \begin{bmatrix} -3 \\ -2 \\ 0 \end{bmatrix}, \quad \mathbf{v}_2 = \begin{bmatrix} -4 \\ 3 \\ -1 \end{bmatrix}, \quad \mathbf{v}_3 = \begin{bmatrix} -5 \\ 0 \\ 2 \end{bmatrix}

Do you want further clarification on any part of the process?

Relative Questions:

  1. How is the null space of a matrix used in solving systems of linear equations?
  2. What role do the arbitrary constants c1c_1 and c2c_2 play in finding solutions?
  3. Can you explain how to determine if a system of equations has infinitely many solutions?
  4. What happens when the null space consists of more than two vectors?
  5. How does changing the values of c1c_1 and c2c_2 affect the solution set?

Tip:

To verify if a vector is a solution, you can substitute it back into the matrix equation to see if it satisfies Ax=b\mathbf{A} \mathbf{x} = \mathbf{b}.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Matrix Equation
Null Space

Formulas

x = v + c1 * [-1, -3, 3] + c2 * [-2, 2, 2]

Theorems

The solution to a matrix equation Ax = b can be written as the sum of a particular solution and a linear combination of vectors from the null space of A.

Suitable Grade Level

College/University level