Math Problem Statement

Let T : R3 → R3 be the linear transformation defined by T (x, y, z) = (x + y, y + z, x + z). Let E = {(1, 0, 0), (0, 1, 0), (0, 0, 1)} be the standard basis for R3, and let B = {(1, 1, 0), (0, 1, 1), (1, 0, 1)} be another basis for R3.

  1. Find the matrix [T ]E of T relative to the basis E. That is [T ]E =    T   1 0 0     E  T   0 1 0     E  T   0 0 1     E  
  2. Find the change-of-basis matrix T E B .
  3. Find the matrix [T ]B of T relative to the basis B. That is [T ]B =    T   1 1 0     B  T   0 1 1     B  T   1 0 1   

Solution

Solution

1. Find the matrix [T]E[T]_E of TT relative to the standard basis EE.

To find [T]E[T]_E, we apply TT to each basis vector in E={(1,0,0),(0,1,0),(0,0,1)}E = \{(1, 0, 0), (0, 1, 0), (0, 0, 1)\} and express the results in terms of the standard basis:

  1. T(1,0,0)=(1+0,0+0,1+0)=(1,0,1)T(1, 0, 0) = (1 + 0, 0 + 0, 1 + 0) = (1, 0, 1).
  2. T(0,1,0)=(0+1,1+0,0+0)=(1,1,0)T(0, 1, 0) = (0 + 1, 1 + 0, 0 + 0) = (1, 1, 0).
  3. T(0,0,1)=(0+0,0+1,0+1)=(0,1,1)T(0, 0, 1) = (0 + 0, 0 + 1, 0 + 1) = (0, 1, 1).

Thus, [T]E[T]_E is:

\begin{bmatrix} 1 & 1 & 0 \\ 0 & 1 & 1 \\ 1 & 0 & 1 \end{bmatrix}.$$ --- #### 2. Find the change-of-basis matrix $$T_E^B$$. The change-of-basis matrix $$T_E^B$$ converts coordinates from the $$B$$-basis to the $$E$$-basis. To find it, write each vector in $$B = \{(1, 1, 0), (0, 1, 1), (1, 0, 1)\}$$ as a linear combination of the standard basis $$E$$. Since $$B$$ is already expressed in $$E$$, the columns of $$T_E^B$$ are just the vectors in $$B$$ expressed in terms of $$E$$: $$T_E^B = \begin{bmatrix} 1 & 0 & 1 \\ 1 & 1 & 0 \\ 0 & 1 & 1 \end{bmatrix}.$$ --- #### 3. Find the matrix $$[T]_B$$ of $$T$$ relative to the basis $$B$$. To compute $$[T]_B$$, we use the relation: \[ [T]_B = (T_E^B)^{-1} \cdot [T]_E \cdot T_E^B. \] First, compute $$(T_E^B)^{-1}$$. Using standard inversion techniques for a $$3 \times 3$$ matrix, we find: $$(T_E^B)^{-1} = \begin{bmatrix} 1 & -1 & -1 \\ -1 & 1 & 0 \\ -1 & 0 & 1 \end{bmatrix}.$$ Next, compute the product $$[T]_E \cdot T_E^B$$: $$[T]_E \cdot T_E^B = \begin{bmatrix} 1 & 1 & 0 \\ 0 & 1 & 1 \\ 1 & 0 & 1 \end{bmatrix} \cdot \begin{bmatrix} 1 & 0 & 1 \\ 1 & 1 & 0 \\ 0 & 1 & 1 \end{bmatrix} = \begin{bmatrix} 2 & 1 & 1 \\ 1 & 2 & 1 \\ 1 & 1 & 2 \end{bmatrix}.$$ Finally, compute: \[ [T]_B = (T_E^B)^{-1} \cdot ([T]_E \cdot T_E^B): \] $$[T]_B = \begin{bmatrix} 1 & -1 & -1 \\ -1 & 1 & 0 \\ -1 & 0 & 1 \end{bmatrix} \cdot \begin{bmatrix} 2 & 1 & 1 \\ 1 & 2 & 1 \\ 1 & 1 & 2 \end{bmatrix} = \begin{bmatrix} 1 & -1 & 0 \\ 0 & 1 & -1 \\ -1 & 0 & 1 \end{bmatrix}.$$ --- ### Final Answers 1. $$[T]_E = \begin{bmatrix} 1 & 1 & 0 \\ 0 & 1 & 1 \\ 1 & 0 & 1 \end{bmatrix}$$. 2. $$T_E^B = \begin{bmatrix} 1 & 0 & 1 \\ 1 & 1 & 0 \\ 0 & 1 & 1 \end{bmatrix}$$. 3. $$[T]_B = \begin{bmatrix} 1 & -1 & 0 \\ 0 & 1 & -1 \\ -1 & 0 & 1 \end{bmatrix}$$. --- Would you like more detailed explanations for any part? Here are some related questions to explore: 1. What is the geometric interpretation of $$[T]_E$$ and $$[T]_B$$? 2. How is the change-of-basis matrix $$T_E^B$$ constructed? 3. Why is matrix multiplication used to find $$[T]_B$$ from $$[T]_E$$? 4. How would you verify that $$[T]_B$$ is correct? 5. What happens if the bases $$E$$ and $$B$$ are not linearly independent? **Tip:** Always ensure that your change-of-basis matrix is invertible before proceeding with computations, as it ensures the new basis is valid!

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Math Problem Analysis

Mathematical Concepts

Linear Transformations
Matrix Representation
Change of Basis
Basis Vectors

Formulas

[T]_E = [T(v1)_E, T(v2)_E, T(v3)_E]
Change-of-basis matrix: T_E^B = [B in terms of E]
[T]_B = (T_E^B)^(-1) · [T]_E · T_E^B

Theorems

Linear Independence and Basis
Matrix Multiplication for Transformation Composition

Suitable Grade Level

Undergraduate Mathematics (Linear Algebra)