Math Problem Statement

Evaluate the determinant of the matrix A = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] and determine if the matrix is invertible.

Solution

The image shows a mathematical problem related to matrix determinants. Here's a transcription of the text:

"Consider a matrix A: A=(123456789)A = \begin{pmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{pmatrix} Evaluate the determinant of A. Check if the matrix is invertible."

To solve this:

1. Determinant of A:

The determinant of a 3x3 matrix AA with elements:

A=(abcdefghi)A = \begin{pmatrix} a & b & c \\ d & e & f \\ g & h & i \end{pmatrix}

is calculated as:

det(A)=a(eifh)b(difg)+c(dheg)\text{det}(A) = a(ei - fh) - b(di - fg) + c(dh - eg)

For the given matrix:

A=(123456789)A = \begin{pmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{pmatrix}

Substituting the values:

[ \text{det}(A) = 1[(5)(9) - (6)(8)] - 2[(4)(9) - (6)(7)] + 3[(4)(8) - (5)(7)] ]

Now, I'll compute the determinant.The determinant of matrix AA is 0.

Conclusion:

  • Since the determinant is 0, the matrix AA is not invertible. A matrix with a zero determinant is called singular and does not have an inverse.

Would you like more details on this, or do you have any other questions?

Here are some follow-up questions to further explore this topic:

  1. How do you find the inverse of a matrix if it is invertible?
  2. What is the significance of a matrix having a determinant of 0?
  3. How do elementary row operations affect the determinant of a matrix?
  4. Can a matrix with a zero determinant still have linearly independent rows or columns?
  5. What are some real-world applications of matrix determinants?

Tip: Always check the determinant of a matrix to quickly determine if it's invertible before attempting to calculate its inverse.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Matrix Determinants

Formulas

det(A) = a(ei - fh) - b(di - fg) + c(dh - eg)

Theorems

Invertibility Theorem (A matrix is invertible if and only if its determinant is non-zero)

Suitable Grade Level

Grades 10-12