Properties of Determinants And Some Important Determinants to Remember

Properties of Determinants:-

Determinant of a matrix is same as the determinant of its transpose.

If two rows or columns of a determinant are interchanged the determinant changes its sign.

If the elements of a row (column) of a determinant are multiplied by a constant K, then the determinant will be multiplied by the same constant. For example,

If A is a square matrix of order n, then

If all the elements of a row (column) of a determinant are zeros, then the value of that determinant is also zero.

If two rows (columns) of a determinant are equal then value of that determinant is zero. Note:- If two rows (2 columns) of a determinant are proportionate then its value is zero.

If the elements of a row (column) of a determinant are sums of two elements then the determinant can be expressed as the sum of two determinants. That is for example,

If the elements of a row (column) of a determinant are added to or subtracted from the corresponding elements of some other row (column) then the determinant remains unchanged.

If the products of the elements of a row (or column) of a determinant with a constant K are added to the corresponding elements of some other row (or column), then the determinant remains unchanged.

Sum of the products of the elements of a row in a square matrix and the co-factors of the corresponding elements of some other row (column) is zero.

If the rows or columns of a determinant are changed without disturbing a cyclic order, then the determinant remains unchanged. That is,

Determinant of a null matrix is 1.

Determinant of a null matrix of the order 3X3 is zero.

Some Important Matrices Determinants to be Remembered for competitive exams:-