36. Suppose a 5 x 6 matrix A has four pivot columns. Wha nullity A? Is Col A = R4? Why or why not?

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
Problem 1RQ
icon
Related questions
Question
100%
**Problem 36:**

Suppose a \(5 \times 6\) matrix \(A\) has four pivot columns. What is the nullity \(A\)? Is \(\text{Col} \, A = \mathbb{R}^4\)? Why or why not?

**Explanations:**

1. **Matrix and Dimensions:**
   - The matrix \(A\) is a \(5 \times 6\) matrix, meaning it has 5 rows and 6 columns.

2. **Pivot Columns:**
   - The matrix has four pivot columns, which are columns of the matrix that contain leading entries (or "pivots") in the row-reduced form of the matrix.

3. **Nullity of A:**
   - Nullity is defined as the number of columns minus the rank of the matrix.
   - Rank is the number of pivot columns, which is given as 4.
   - Thus, nullity of \(A = \text{Number of columns} - \text{Rank} = 6 - 4 = 2\).

4. **Column Space:**
   - \(\text{Col} \, A\) refers to the column space of \(A\), which is the set of all possible linear combinations of its column vectors.
   - Since \(A\) is a \(5 \times 6\) matrix and has 4 pivot columns, the dimension of \(\text{Col} \, A\) is 4.
   - However, \(\text{Col} \, A\) consists of vectors that are in \(\mathbb{R}^5\), not \(\mathbb{R}^4\), because the columns of \(A\) are 5-dimensional vectors.
  
Therefore, \(\text{Col} \, A\) cannot be equal to \(\mathbb{R}^4\). The column space \(\text{Col} \, A\) is actually a 4-dimensional subspace of \(\mathbb{R}^5\).
Transcribed Image Text:**Problem 36:** Suppose a \(5 \times 6\) matrix \(A\) has four pivot columns. What is the nullity \(A\)? Is \(\text{Col} \, A = \mathbb{R}^4\)? Why or why not? **Explanations:** 1. **Matrix and Dimensions:** - The matrix \(A\) is a \(5 \times 6\) matrix, meaning it has 5 rows and 6 columns. 2. **Pivot Columns:** - The matrix has four pivot columns, which are columns of the matrix that contain leading entries (or "pivots") in the row-reduced form of the matrix. 3. **Nullity of A:** - Nullity is defined as the number of columns minus the rank of the matrix. - Rank is the number of pivot columns, which is given as 4. - Thus, nullity of \(A = \text{Number of columns} - \text{Rank} = 6 - 4 = 2\). 4. **Column Space:** - \(\text{Col} \, A\) refers to the column space of \(A\), which is the set of all possible linear combinations of its column vectors. - Since \(A\) is a \(5 \times 6\) matrix and has 4 pivot columns, the dimension of \(\text{Col} \, A\) is 4. - However, \(\text{Col} \, A\) consists of vectors that are in \(\mathbb{R}^5\), not \(\mathbb{R}^4\), because the columns of \(A\) are 5-dimensional vectors. Therefore, \(\text{Col} \, A\) cannot be equal to \(\mathbb{R}^4\). The column space \(\text{Col} \, A\) is actually a 4-dimensional subspace of \(\mathbb{R}^5\).
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 2 steps

Blurred answer
Recommended textbooks for you
Advanced Engineering Mathematics
Advanced Engineering Mathematics
Advanced Math
ISBN:
9780470458365
Author:
Erwin Kreyszig
Publisher:
Wiley, John & Sons, Incorporated
Numerical Methods for Engineers
Numerical Methods for Engineers
Advanced Math
ISBN:
9780073397924
Author:
Steven C. Chapra Dr., Raymond P. Canale
Publisher:
McGraw-Hill Education
Introductory Mathematics for Engineering Applicat…
Introductory Mathematics for Engineering Applicat…
Advanced Math
ISBN:
9781118141809
Author:
Nathan Klingbeil
Publisher:
WILEY
Mathematics For Machine Technology
Mathematics For Machine Technology
Advanced Math
ISBN:
9781337798310
Author:
Peterson, John.
Publisher:
Cengage Learning,
Basic Technical Mathematics
Basic Technical Mathematics
Advanced Math
ISBN:
9780134437705
Author:
Washington
Publisher:
PEARSON
Topology
Topology
Advanced Math
ISBN:
9780134689517
Author:
Munkres, James R.
Publisher:
Pearson,