Math Problem Statement

Verify the identity det(AB) = det(A) * det(B) for matrices A and B. A = [[4, -1], [2, -0.125]], B = [[-0.5, 2], [4, 8]]

Solution

In the provided image, you are asked to verify the identity:

det(AB)=det(A)det(B)\text{det}(AB) = \text{det}(A) \cdot \text{det}(B)

for two given matrices AA and BB:

A=(4120.125),B=(0.5248).A = \begin{pmatrix} 4 & -1 \\ 2 & -0.125 \end{pmatrix}, \quad B = \begin{pmatrix} -0.5 & 2 \\ 4 & 8 \end{pmatrix}.

Steps to solve:

  1. Calculate det(A)\text{det}(A): The determinant of a 2x2 matrix A=(abcd)A = \begin{pmatrix} a & b \\ c & d \end{pmatrix} is given by:

    det(A)=adbc\text{det}(A) = ad - bc

  2. Calculate det(B)\text{det}(B): Use the same formula for matrix BB.

  3. Multiply matrices AA and BB: Perform matrix multiplication to compute ABAB.

  4. Calculate det(AB)\text{det}(AB): After finding ABAB, compute its determinant.

  5. Compare: Check if det(AB)\text{det}(AB) is equal to det(A)det(B)\text{det}(A) \cdot \text{det}(B).

Let me calculate these values for you.Here are the results:

  1. det(A)=1.5\text{det}(A) = 1.5
  2. det(B)=12.0\text{det}(B) = -12.0
  3. The product det(A)det(B)=1.5×12.0=18.0\text{det}(A) \cdot \text{det}(B) = 1.5 \times -12.0 = -18.0
  4. det(AB)=18.0\text{det}(AB) = -18.0 (approximately 17.999999999999996-17.999999999999996 due to rounding).

Thus, the identity det(AB)=det(A)det(B)\text{det}(AB) = \text{det}(A) \cdot \text{det}(B) holds true for the given matrices.

Would you like a deeper explanation of the steps?

Here are 5 related questions:

  1. How is the determinant of a 2x2 matrix derived?
  2. What happens when one of the matrices has a zero determinant?
  3. Can this identity be extended to larger matrices?
  4. How would rounding affect larger matrices in determinant calculations?
  5. What other matrix identities are important to know?

Tip: When working with floating-point numbers, slight differences in results can occur due to rounding errors, especially in large calculations.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Linear Algebra
Determinants
Matrix Multiplication

Formulas

det(A) = ad - bc
det(AB) = det(A) * det(B)
Matrix multiplication formula

Theorems

Determinant multiplication theorem

Suitable Grade Level

Undergraduate Mathematics or Advanced High School (Grades 11-12)