Math Problem Statement

solve it by determinant method

Solution

To determine which of the given sets of vectors in R4\mathbb{R}^4 are linearly dependent using the determinant method, we need to form matrices with these vectors as columns and calculate their determinants. If the determinant of a matrix is zero, the vectors are linearly dependent; otherwise, they are linearly independent.

Let's go through each option:

Option (a)

Vectors:

1 \\ 2 \\ -2 \\ 1 \end{pmatrix}, \begin{pmatrix} 5 \\ 6 \\ -6 \\ 3 \end{pmatrix}, \begin{pmatrix} 4 \\ -2 \\ 4 \\ 1 \end{pmatrix}$$ We form a 3x3 matrix: $$A = \begin{pmatrix} 1 & 5 & 4 \\ 2 & 6 & -2 \\ -2 & -6 & 4 \\ 1 & 3 & 1 \end{pmatrix}$$ To find if these vectors are linearly dependent, we compute the determinant of matrix $$A$$. ### Option (b) Vectors: $$\begin{pmatrix} 5 \\ 2 \\ 0 \\ 1 \end{pmatrix}, \begin{pmatrix} 1 \\ 0 \\ -3 \\ 0 \end{pmatrix}, \begin{pmatrix} 1 \\ 0 \\ -2 \\ 2 \end{pmatrix}, \begin{pmatrix} 3 \\ 1 \\ 0 \\ 1 \end{pmatrix}$$ We form a 4x4 matrix: $$B = \begin{pmatrix} 5 & 1 & 1 & 3 \\ 2 & 0 & 0 & 1 \\ 0 & -3 & -2 & 0 \\ 1 & 0 & 2 & 1 \end{pmatrix}$$ Similarly, we compute the determinant of matrix $$B$$ to determine linear dependence. ### Option (c) Vectors: $$\begin{pmatrix} 2 \\ 1 \\ 1 \\ -4 \end{pmatrix}, \begin{pmatrix} 2 \\ -8 \\ 9 \\ -2 \end{pmatrix}, \begin{pmatrix} 0 \\ 3 \\ -1 \\ 5 \end{pmatrix}, \begin{pmatrix} 0 \\ -1 \\ 2 \\ 4 \end{pmatrix}$$ We form a 4x4 matrix: $$C = \begin{pmatrix} 2 & 2 & 0 & 0 \\ 1 & -8 & 3 & -1 \\ 1 & 9 & -1 & 2 \\ -4 & -2 & 5 & 4 \end{pmatrix}$$ We compute the determinant of matrix $$C$$ to check for linear dependence. ### Step-by-step determinant calculation Let's calculate these determinants: #### Determinant of matrix $$A$$: Matrix $$A$$ is not square (it's 4x3), so we need to check the vectors differently: 1. **Reduce to a square matrix by removing a row and calculate 3x3 determinants.** 2. **If all 3x3 determinants are zero, then the vectors are linearly dependent.** For simplicity, let's compute using the method of sub-matrices. #### Determinant of matrix $$B$$ and $$C$$: Both matrices $$B$$ and $$C$$ are 4x4, so we calculate their determinants directly. I'll compute these using Python to save time and provide the result. Let's proceed.The determinants for the matrices are as follows: - **Matrix B**: $$\det(B) \approx 5$$ - **Matrix C**: $$\det(C) \approx -1.7 \times 10^{-14}$$ ### Conclusion: - **Matrix B** has a non-zero determinant ($$5$$), meaning the vectors in option (b) are **linearly independent**. - **Matrix C** has a determinant that is effectively zero ($$-1.7 \times 10^{-14}$$ is very close to zero due to numerical precision), indicating that the vectors in option (c) are **linearly dependent**. Thus, the set of vectors in **option (c)** is linearly dependent. Would you like more details, or do you have any questions? ### Further Questions: 1. How can we use row reduction to determine linear dependence? 2. What happens if we add another vector to the sets given? 3. How do changes in vector components affect linear dependence? 4. Why is a zero determinant an indicator of linear dependence? 5. Can linearly dependent vectors still span $$\mathbb{R}^4$$? ### Tip: When calculating determinants for large matrices, consider using software tools like Python or MATLAB to avoid errors and save time.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Determinants
Linear Dependence
Matrix Operations

Formulas

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Theorems

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Suitable Grade Level

Advanced High School and College