Math Problem Statement

explain in detail what happens here

explain in detail what happens here

Solution

From analyzing the content of the image, here’s a detailed explanation of the mathematical process shown:


The main focus here appears to be solving a system of linear equations using matrix analysis—specifically, the concept of determinants to determine whether the system is compatible (has solutions) or incompatible (no solutions).


Steps and Explanation:

  1. Matrix AA and Its Determinant:
    • The matrix AA is given as: \begin{bmatrix} 2 & -3 & 1 \\ 1 & 2 & -1 \\ 2 & 2 & 1 \end{bmatrix}.$$
    • The determinant of AA (det(A)\text{det}(A)) is calculated using the formula for a 3x3 matrix: a(ei − fh) − b(di − fg) + c(dh − eg).$$ Substituting the elements of $$A$$: $$\text{det}(A) = 2 \cdot (2 \cdot 1 - (-1) \cdot 2) - (-3) \cdot (1 \cdot 1 - (-1) \cdot 2) + 1 \cdot (1 \cdot 2 - 2 \cdot 2).$$ Simplifying: $$\text{det}(A) = 2 \cdot (2 + 2) - (-3) \cdot (1 + 2) + 1 \cdot (2 - 4),$$ $$\text{det}(A) = 2 \cdot 4 + 3 \cdot 3 - 2,$$ $$\text{det}(A) = 8 + 9 - 2 = 15.$$ So, $$\text{det}(A) = 15$$.
    • Since det(A)0\text{det}(A) \neq 0, matrix AA is invertible, and the system of linear equations is compatible (it has a unique solution).

  1. Setting Up the System:
    • The augmented matrix for the system appears to be given, but details of the specific equations and right-hand side vector (b\mathbf{b}) aren't fully clear in this image. Nonetheless, the determinant's non-zero value ensures that the system has a unique solution, and no further checks for compatibility are needed.

  1. System Analysis (Alternative Scenario):
    • The image also shows a scenario where the determinant is zero. When det(A)=0\text{det}(A) = 0, it is concluded that the system is incompatible (no solution) or possibly dependent (infinitely many solutions). This depends on the rank of the augmented matrix.

    • However, as calculated, det(A)0\text{det}(A) \neq 0, so the system remains compatible with a unique solution.


  1. Conclusion:
    • The determinant det(A)\text{det}(A) serves as the deciding factor for the solvability of the system. Here, because det(A)0\text{det}(A) \neq 0, the matrix is invertible, and the system is consistent with a unique solution.

Additional Concepts Highlighted:

  • Determinant Properties:

    • A determinant of 0 indicates the matrix is singular (non-invertible), leading to an incompatible or dependent system.
    • A non-zero determinant implies an invertible matrix, guaranteeing a unique solution.
  • System Compatibility:

    • Compatible systems have at least one solution (unique or infinite).
    • Incompatible systems have no solution.

Do you want me to clarify any specific part of this explanation, or go further into solving a similar system?


Related Questions:

  1. How is the determinant of a 3x3 matrix calculated step by step?
  2. What are the implications of det(A)=0\text{det}(A) = 0 for the solution of a linear system?
  3. What methods other than determinants can be used to analyze a system's compatibility (e.g., row reduction)?
  4. How does the rank of a matrix relate to the solution of a system of equations?
  5. What are the geometrical interpretations of compatible and incompatible systems?

Tip:

When working with determinants and matrices, always verify your computations step by step to avoid errors in sign or arithmetic, as these can change the outcome significantly.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Matrix Determinants
System of Linear Equations
Compatibility of Systems

Formulas

Determinant of a 3x3 matrix: det(A) = a(ei − fh) − b(di − fg) + c(dh − eg)

Theorems

Invertible Matrix Theorem: A matrix is invertible if and only if its determinant is non-zero.

Suitable Grade Level

Grades 10-12