Solved: Det of 4A-1 | Find Det of 4A-1 Matrix

  • Thread starter Vagrant
  • Start date
  • Tags
    Determinant
In summary, a determinant is a numerical value that can be calculated from a square matrix and is used to determine important properties of the matrix. To find the determinant of a matrix, you can use various methods such as cofactor expansion, row reduction, or the Leibniz formula. The term "det of 4A-1" refers to the determinant of the matrix 4A-1, which has been multiplied by 4 and subtracted by the identity matrix. It is important to find the determinant of a matrix because it can provide valuable information about the matrix, such as its invertibility and the ability to calculate the area or volume of a geometric shape. The determinant of a matrix can also be negative, depending on the
  • #1
Vagrant
195
1
[SOLVED] Determinant problem

Homework Statement


If det(A) = 7, then what is det(4 A-1)?
where A is 3*3 matrix

Homework Equations


The Attempt at a Solution



No idea about this, please give me some hint.
 
Physics news on Phys.org
  • #2
This is just collecting properties about determinants. If you scale one of your rows (or columns) by some scalar what is the determinant of the resulting matrix? Now, realize that 4A is multiplying every row by 4. Assuming A has an inverse, what is the determinant of the inverse?
 
  • #3


I would first clarify the question and make sure I understand what is being asked. It seems that the question is asking for the determinant of a matrix (4A-1) where A is a 3x3 matrix and the determinant of A is given to be 7.

To solve this problem, I would first recall the properties of determinants, specifically the property that the determinant of a scalar multiple of a matrix is equal to the scalar multiplied by the determinant of the original matrix. In this case, we have a scalar multiple of A, which is 4A, and we are subtracting 1 from the matrix.

Using this property, we can rewrite the expression as 4(det(A))-1. Since we are given that det(A) = 7, we can plug that in and get 4(7)-1 = 28-1 = 27. Therefore, the determinant of 4A-1 is 27.

In summary, the determinant of 4A-1 is 27.
 

Related to Solved: Det of 4A-1 | Find Det of 4A-1 Matrix

1. What is a determinant?

A determinant is a numerical value that can be calculated from a square matrix. It is used to determine important properties of the matrix, such as whether it is invertible or singular.

2. How do you find the determinant of a matrix?

The determinant of a matrix can be found by following a specific set of steps, depending on the size of the matrix. For a 2x2 matrix, you can simply multiply the diagonal elements and subtract the product of the off-diagonal elements. For larger matrices, you can use various methods such as cofactor expansion, row reduction, or using the Leibniz formula.

3. What does "det of 4A-1" mean in the context of a matrix?

In this context, "det of 4A-1" refers to the determinant of the matrix 4A-1. This means that the given matrix has been multiplied by the scalar value of 4 and then subtracted by the identity matrix (a matrix with all diagonal elements equal to 1 and all other elements equal to 0).

4. Why is it important to find the determinant of a matrix?

The determinant of a matrix is important because it can provide valuable information about the matrix. For example, a non-zero determinant indicates that the matrix is invertible, which means it has a unique solution for a system of linear equations. It can also be used to calculate the area or volume of a geometric shape represented by the matrix.

5. Can the determinant of a matrix be negative?

Yes, the determinant of a matrix can be negative. The sign of the determinant depends on the arrangement of the elements in the matrix. For example, a 2x2 matrix with a negative determinant would have a negative product of the diagonal elements and a positive product of the off-diagonal elements.

Similar threads

  • Precalculus Mathematics Homework Help
Replies
6
Views
1K
  • Precalculus Mathematics Homework Help
Replies
7
Views
2K
  • Precalculus Mathematics Homework Help
Replies
23
Views
2K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
5
Views
1K
  • Linear and Abstract Algebra
Replies
20
Views
1K
  • Linear and Abstract Algebra
Replies
2
Views
1K
  • Calculus and Beyond Homework Help
Replies
25
Views
2K
  • Precalculus Mathematics Homework Help
Replies
3
Views
2K
  • Precalculus Mathematics Homework Help
Replies
9
Views
2K
  • Precalculus Mathematics Homework Help
Replies
32
Views
961
Back
Top