Math Problem Statement

Solve the matrix equation \( A \cdot X = B \), where \( A = \begin{pmatrix} 3 & 2 \\ -5 & -3 \end{pmatrix} \) and \( B = \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix} \).

Solution

The given problem involves solving a matrix equation to find matrix XX. The equation is:

(3253)X=(1234)\begin{pmatrix} 3 & 2 \\ -5 & -3 \end{pmatrix} \cdot X = \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix}

To solve for XX, we can rewrite the equation as:

X=(3253)1(1234)X = \begin{pmatrix} 3 & 2 \\ -5 & -3 \end{pmatrix}^{-1} \cdot \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix}

Steps:

  1. Find the inverse of the matrix A=(3253)A = \begin{pmatrix} 3 & 2 \\ -5 & -3 \end{pmatrix}: The formula for the inverse of a 2x2 matrix is:

    A1=1det(A)(dbca),A^{-1} = \frac{1}{\text{det}(A)} \cdot \begin{pmatrix} d & -b \\ -c & a \end{pmatrix},

    where A=(abcd)A = \begin{pmatrix} a & b \\ c & d \end{pmatrix}.

    For A=(3253)A = \begin{pmatrix} 3 & 2 \\ -5 & -3 \end{pmatrix}:

    • Determinant det(A)=(3)(3)(5)(2)=9+10=1\text{det}(A) = (3)(-3) - (-5)(2) = -9 + 10 = 1.

    • Inverse:

      A1=(3253).A^{-1} = \begin{pmatrix} -3 & -2 \\ 5 & 3 \end{pmatrix}.

  2. Multiply the inverse matrix A1A^{-1} with B=(1234)B = \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix}:

    X=(3253)(1234).X = \begin{pmatrix} -3 & -2 \\ 5 & 3 \end{pmatrix} \cdot \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix}.

    Performing the matrix multiplication:

    X=((3)(1)+(2)(3)(3)(2)+(2)(4)(5)(1)+(3)(3)(5)(2)+(3)(4))X = \begin{pmatrix} (-3)(1) + (-2)(3) & (-3)(2) + (-2)(4) \\ (5)(1) + (3)(3) & (5)(2) + (3)(4) \end{pmatrix}

    X=(36685+910+12)X = \begin{pmatrix} -3 - 6 & -6 - 8 \\ 5 + 9 & 10 + 12 \end{pmatrix}

    X=(9141422).X = \begin{pmatrix} -9 & -14 \\ 14 & 22 \end{pmatrix}.

Final Answer:

X=(9141422).X = \begin{pmatrix} -9 & -14 \\ 14 & 22 \end{pmatrix}.

If you need further explanation or have more questions, let me know! Here are related questions for deeper understanding:

  1. How is the determinant of a 2x2 matrix calculated?
  2. Why do we use the inverse of a matrix to solve such equations?
  3. Can this method be extended to higher-order matrices?
  4. What happens if the determinant of a matrix is zero?
  5. How can we verify the solution of a matrix equation?

Tip: Always check the

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Math Problem Analysis

Mathematical Concepts

Matrix Algebra
Matrix Inverse
Matrix Multiplication
Determinants

Formulas

Matrix Inverse: A^{-1} = (1/det(A)) * \begin{pmatrix} d & -b \\ -c & a \end{pmatrix}
Matrix Multiplication: C = A \cdot B, \text{where } C_{ij} = \sum_k A_{ik}B_{kj}

Theorems

Inverse of a Matrix (for 2x2 matrices)
Matrix Multiplication Theorem

Suitable Grade Level

Grades 11-12