Math Problem Statement

Find 2×2 matrices a,b,c for which ca=bc where a≠b

Solution

To find 2×22 \times 2 matrices AA, BB, and CC such that CA=BCCA = BC and ABA \neq B, we can approach this problem by constructing an example with specific matrices.

Let's take:

A=(1000),B=(0001),C=(0110)A = \begin{pmatrix} 1 & 0 \\ 0 & 0 \end{pmatrix}, \quad B = \begin{pmatrix} 0 & 0 \\ 0 & 1 \end{pmatrix}, \quad C = \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix}

Now let's verify if these matrices satisfy the equation CA=BCCA = BC:

  1. Compute CACA: CA=(0110)(1000)=(0010)CA = \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix} \begin{pmatrix} 1 & 0 \\ 0 & 0 \end{pmatrix} = \begin{pmatrix} 0 & 0 \\ 1 & 0 \end{pmatrix}

  2. Compute BCBC: BC=(0001)(0110)=(0010)BC = \begin{pmatrix} 0 & 0 \\ 0 & 1 \end{pmatrix} \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix} = \begin{pmatrix} 0 & 0 \\ 1 & 0 \end{pmatrix}

Since CA=BC=(0010)CA = BC = \begin{pmatrix} 0 & 0 \\ 1 & 0 \end{pmatrix}, the condition CA=BCCA = BC is satisfied. Furthermore, ABA \neq B, as required.

Summary

Thus, the matrices AA, BB, and CC given by:

A=(1000),B=(0001),C=(0110)A = \begin{pmatrix} 1 & 0 \\ 0 & 0 \end{pmatrix}, \quad B = \begin{pmatrix} 0 & 0 \\ 0 & 1 \end{pmatrix}, \quad C = \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix}

satisfy CA=BCCA = BC with ABA \neq B.

Would you like further details or have any other questions?


Here are 5 related questions to expand on this:

  1. What is the significance of the condition ABA \neq B in matrix equations?
  2. Can you generalize the condition CA=BCCA = BC for larger matrices?
  3. How does the commutative property apply to matrix multiplication?
  4. What are the eigenvalues of the matrices AA and BB in this example?
  5. Can this problem be solved if matrices AA, BB, and CC are diagonal?

Tip: When dealing with matrix equations, always verify the dimensions of matrices before performing operations like multiplication or addition.

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Math Problem Analysis

Mathematical Concepts

Matrix Algebra
Matrix Multiplication
Commutative Property of Matrices

Formulas

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Theorems

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Suitable Grade Level

Undergraduate Level