Is there any relation between the value of determinant and the invertibility of matrix in linear algebra?

Is there any relation between the value of determinant and the invertibility of matrix in linear algebra?


yes
However, a conditional matrix A is invertible if and only if the value of its determinant | a | is not equal to 0
A ^ (- 1) = (1 / | a |) × a *, where a ^ (- 1) represents the inverse matrix of matrix A, where | a | is the determinant of matrix A, and a * is the adjoint matrix of matrix A



We have known the eigenvalues 1,2, - 1 of the matrix of order 3. Find the value of the determinant | a * a * a + 2a-4e |
This is an example in the textbook, but I can't understand it


The cube with eigenvalues of 1 plus 2 times 1 minus 4 is equal to - 1. Similarly, the other two cubes with eigenvalues of 2 plus 2 times 2 minus 4 are equal to 8, and the third eigenvalue is - 7. Therefore, the value of the determinant is - 1 times 8 and - 7 times 56



Let the determinant of the third-order square matrix a be equal to 2, then 3A *=


|3A*|=3^3 *|A*|= 3^3 * |A|^(3-1)= 27*4 =108