Math Problem Statement

A system of three linear equations is represented by the following matrix equation: \[ A \cdot \vec{x} = \vec{b} \] where: \[ A = \begin{bmatrix} 4 & -3 & 2 \\ -1 & 3 & -4 \\ 2 & 1 & -3 \end{bmatrix}, \quad \vec{b} = \begin{bmatrix} 0 \\ -7 \\ -8 \end{bmatrix} \] The inverse of matrix \( A \) is given as: \[ A^{-1} = \begin{bmatrix} 5 & 7 & -6 \\ 11 & 16 & -14 \\ 7 & 10 & -9 \end{bmatrix} \] Solve the system and find the values of \( x \), \( y \), and \( z \).

Solution

To solve this system of equations using the given inverse of matrix AA, the solution can be calculated as:

x=A1b\vec{x} = A^{-1} \cdot \vec{b}

Step-by-step solution:

  1. Matrix Multiplication:

    \begin{bmatrix} 5 & 7 & -6 \\ 11 & 16 & -14 \\ 7 & 10 & -9 \end{bmatrix}, \quad \vec{b} = \begin{bmatrix} 0 \\ -7 \\ -8 \end{bmatrix}.$$ Compute the product $$A^{-1} \cdot \vec{b}$$: $$A^{-1} \cdot \vec{b} = \begin{bmatrix} 5 & 7 & -6 \\ 11 & 16 & -14 \\ 7 & 10 & -9 \end{bmatrix} \cdot \begin{bmatrix} 0 \\ -7 \\ -8 \end{bmatrix}.$$
  2. Perform Element-wise Calculation: Row 1: 5(0)+7(7)+(6)(8)=49+48=1.\text{Row 1: } 5(0) + 7(-7) + (-6)(-8) = -49 + 48 = -1. Row 2: 11(0)+16(7)+(14)(8)=112+112=0.\text{Row 2: } 11(0) + 16(-7) + (-14)(-8) = -112 + 112 = 0. Row 3: 7(0)+10(7)+(9)(8)=70+72=2.\text{Row 3: } 7(0) + 10(-7) + (-9)(-8) = -70 + 72 = 2.

  3. Solution Vector:

    \begin{bmatrix} x \\ y \\ z \end{bmatrix} = \begin{bmatrix} -1 \\ 0 \\ 2 \end{bmatrix}.$$

Final Answer:

x=1,y=0,z=2.x = -1, \quad y = 0, \quad z = 2.

Let me know if you want additional details on matrix multiplication or have other questions. Here are related questions to explore:

  1. How is the inverse of a matrix calculated?
  2. What conditions make a matrix invertible?
  3. Can this problem be solved using other methods, such as Gaussian elimination?
  4. What happens if the determinant of AA is zero?
  5. How are systems of equations applied in real-world problems?

Tip: Always check the determinant of a matrix before attempting to find its inverse to ensure it is invertible.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Matrix Multiplication
Inverse of a Matrix

Formulas

\( \vec{x} = A^{-1} \cdot \vec{b} \)
Matrix multiplication

Theorems

Inverse Matrix Theorem

Suitable Grade Level

Grades 10-12