Math Problem Statement

Diketahui persamaan matriks berikut: \[ \begin{pmatrix} 3 & 2 \\ -5 & -3 \end{pmatrix} \cdot X = \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix}, \] dengan ordo \( X_{2x2} \). Matriks \( X \) adalah?

Solution

The given matrix equation is:

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

The task is to find XX, which is a 2×22 \times 2 matrix.

To solve for XX, we multiply both sides of the equation by the inverse of the matrix (3253)\begin{pmatrix} 3 & 2 \\ -5 & -3 \end{pmatrix}:

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

Step 1: Compute the inverse of (3253)\begin{pmatrix} 3 & 2 \\ -5 & -3 \end{pmatrix}

The formula for the inverse of a 2×22 \times 2 matrix (abcd)\begin{pmatrix} a & b \\ c & d \end{pmatrix} is:

Inverse=1adbc(dbca).\text{Inverse} = \frac{1}{ad - bc} \cdot \begin{pmatrix} d & -b \\ -c & a \end{pmatrix}.

For (3253)\begin{pmatrix} 3 & 2 \\ -5 & -3 \end{pmatrix}, we have:

  • a=3a = 3, b=2b = 2, c=5c = -5, d=3d = -3,
  • Determinant (adbcad - bc) = (3)(3)(2)(5)=9+10=1(3)(-3) - (2)(-5) = -9 + 10 = 1.

The inverse is:

Inverse=(3253).\text{Inverse} = \begin{pmatrix} -3 & -2 \\ 5 & 3 \end{pmatrix}.

Step 2: Multiply the inverse with (1234)\begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix}

Perform the matrix multiplication:

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

The computation is as follows:

  • Top left: (3)(1)+(2)(3)=36=9(-3)(1) + (-2)(3) = -3 - 6 = -9,
  • Top right: (3)(2)+(2)(4)=68=14(-3)(2) + (-2)(4) = -6 - 8 = -14,
  • Bottom left: (5)(1)+(3)(3)=5+9=14(5)(1) + (3)(3) = 5 + 9 = 14,
  • Bottom right: (5)(2)+(3)(4)=10+12=22(5)(2) + (3)(4) = 10 + 12 = 22.

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

Final Answer:

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

Let me know if you want further explanation or help!


Related Questions:

  1. How is the determinant of a 2×22 \times 2 matrix calculated?
  2. Why is the inverse of a matrix important in solving linear equations?
  3. How do you verify that two matrices are inverses of each other?
  4. What happens if the determinant of a matrix is zero?
  5. How can you compute the inverse of larger matrices (e.g., 3×33 \times 3)?

Tip:

Always double-check the determinant before attempting to find the inverse of a matrix. If the determinant is zero, the matrix does not have an inverse!

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Math Problem Analysis

Mathematical Concepts

Matrix Algebra
Inverse of a Matrix
Matrix Multiplication

Formulas

Inverse of a 2x2 matrix: \( \text{Inverse} = \frac{1}{ad - bc} \cdot \begin{pmatrix} d & -b \\ -c & a \end{pmatrix} \)
Matrix multiplication formula

Theorems

Properties of Inverses in Matrix Algebra

Suitable Grade Level

Grades 10-12