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To answer this question, let me establish an example 3 x 3 matrix named "A":
A= [a b c]
[d e f]
[g h i]
The formula I will give you, called co-factor expansion, works for any size square matrix, so you could use it to find the determinant of a 2 x 2, 3 x 3, all the way up to an n x n matrix. To find the determinant, pick any row or column in the matrix. It will make your work much easier if you choose a row or column that has many zeroes in it.
A general notation that is often used to find the determinant of a matrix is to use straight bars in place of the brackets surrounding the matrix contents. So, if I was to say mathematically that I was finding the determinant of the above example matrix, I could write it as:
det(A)= |a b c|
|d e f|
|g h i|
This notation will be used in the formula, so it is important to know this.
For the sake of an arbitrary example, let us suppose I chose Row 1 of the matrix as my chosen row. To find the determinant of this matrix, I will perform the following calculation:
(-1)2(a)|e f| + (-1)3(b)|d f| + (-1)4(c)|d e|
|h i| |g i| |g h|
This is the specific application of this general formula to the example matrix:
(-1)i+j(aij)det(A1)
In this formula, i and j are the row and column addresses, respectively, of a given matrix element. So, like in our specific application, when Row 1 was chosen as our subject row, the first term was (-1)1+1(A11)det(A1). The element "a" is in the first row, first column of the matrix, mean i=1 and j=1, therefore the superscript of (-1) is 1+1=2. A11 is simply the value held in the address i=1, j=1 of the matrix A. For this application, A11 was "a". det(A1) is the determinant of the submatrix A1. This submatrix has no formal nomenclature, I simply call it this for ease of explanation. A1 is the matrix created by "crossing out" the row and column that belong to the matrix element A11. In this application, that means it is the submatrix that is left after crossing out a, b, c, d, and g, which is simply the 2 x 2 matrix e,f;h,i. Performing this same process for the remainder of the matrix elements in Row 1 will yield the determinant of the matrix. So, the "generalized" form of the specific application above is:
(-1)1+1(A11)det(A1) + (-1)1+2(A12)det(A2) + (-1)1+3(A13)det(A3)
where A1 is the submatrix created by crossing out Row 1 and Column 1, A2 is the submatrix created by crossing out Row 1 and Column 2, and A3 is the submatrix created by crossing out Row 1 and Column 3.
A final note is how to calculate the determinants of the submatrices. For a 3 x 3 matrix, its submatrices are all 2 x 2. For 2 x 2 matrices, a simple formula exists that makes this easy:
|a b| = (ad) - (bc)
|c d|
For higher-dimension matrices, the submatrices also become larger, making the computation much more intensive.
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∙ 13y ago
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What is the physical meaning of determinant of a matrix?
for a 3x3 matrix, it can be interpreted as the volume of the hexahedron formed by three vectors (each row of the matrix as one vector).
What is the determinant rank of the determinant of 123456 its a 2 x 3 matrix?
A determinant is defined only for square matrices, so a 2x3 matrix does not have a determinant.Determinants are defined only for square matrices, so a 2x3 matrix does not have a determinant.
What is the formula for the determinant of a 3 x 3 matrix?
If the matrix is { a1 b1 c1} {a2 b2 c2} {a3 b3 c3} then the determinant is a1b2c3 + b1c2a3 + c1a2b3 - (c1b2a3 + a1c2b3 + b1a2c3)
How many minors are there of a 3x4 order matrix?
A minor is a determinant and a determinant is a value associated with a square matrix.The matrix from which a minor is calculated is formed from a matrix by removing at least one of its rows or columns.We are discussing matrices of 3 rows and 4 columns. The minimum change one can make is to remove a single column. This can be done in four ways, yielding four minors. Each of these four ways yields a 3x3 matrix. There are nine minors in a 3x3 matrix.Hence, the total number of minors is 4 + 4(9)=40.
If two rows of a matrix are interchanged what is true of the resulting determinant?
The determinant will change sign.
What is the determinant of a 3x3 matrix?
It is the product of the three diagonal elements.
What is the determinant of a 3x3 diagonal matrix?
It is the product of the three diagonal elements.
What is the meaning of determinant of a matrix?
for a 3x3 matrix, it can be interpreted as the volume of the hexahedron formed by three vectors (each row of the matrix as one vector).
What is meant by the determinant of a math equation?
A single math equation does not have a determinant. A system of equations (3x3 , 4x4, etc.) will have a determinant. You can find a determinant of a system by converting the system into a corresponding matrix and finding its determinant.
What is the determinant of the matrix 241142335?
Assuming the matrix is a 3x3 matrix of 1-digit number, it is 23. Otherwise it depends on how the 9 digits split up.
What is the physical meaning of determinant of a matrix?
for a 3x3 matrix, it can be interpreted as the volume of the hexahedron formed by three vectors (each row of the matrix as one vector).
What is the determinant rank of the determinant of 123456 its a 2 x 3 matrix?
A determinant is defined only for square matrices, so a 2x3 matrix does not have a determinant.Determinants are defined only for square matrices, so a 2x3 matrix does not have a determinant.
What is the determinant of a 2x3 matrix?
The determinant function is only defined for an nxn (i.e. square) matrix. So by definition of the determinant it would not exist for a 2x3 matrix.
What is the formula for the determinant of a 3 x 3 matrix?
If the matrix is { a1 b1 c1} {a2 b2 c2} {a3 b3 c3} then the determinant is a1b2c3 + b1c2a3 + c1a2b3 - (c1b2a3 + a1c2b3 + b1a2c3)
How many minors are there of a 3x4 order matrix?
A minor is a determinant and a determinant is a value associated with a square matrix.The matrix from which a minor is calculated is formed from a matrix by removing at least one of its rows or columns.We are discussing matrices of 3 rows and 4 columns. The minimum change one can make is to remove a single column. This can be done in four ways, yielding four minors. Each of these four ways yields a 3x3 matrix. There are nine minors in a 3x3 matrix.Hence, the total number of minors is 4 + 4(9)=40.
Can a 3 by 3 matrix equal zero?
First we need to ask what you mean by a matrix equalling a number? A matrix is a rectangular array of numbers all of which might be zero and this is called the zero matrix. We can take the determinant of a square matrix such as a 3x3 and this may be zero even without the entries being zero.
Why does the rule of sarrus work only for a 3 by 3 matrix?
In theory, a 2x2 determinant requires the evaluation of 2 products, a 3x3 determinant requires 6 products, a 4x4 determinant requires 24 products (note: that is the factorial function). The Rule of Sarrus is just a convenient memory aid for this specific case.
