{"id":5059,"date":"2021-09-05T16:00:32","date_gmt":"2021-09-05T10:30:32","guid":{"rendered":"https:\/\/mathemerize.com\/?p=5059"},"modified":"2022-10-01T22:33:09","modified_gmt":"2022-10-01T17:03:09","slug":"determinants-of-matrix-3x3","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/determinants-of-matrix-3x3\/","title":{"rendered":"Determinants of Matrix 3×3 with Examples"},"content":{"rendered":"
Here you will learn how to find determinants of matrix 3×3 with examples.<\/p>\n
Let’s begin –<\/p>\n
If A = \\(\\begin{bmatrix} a_{11} & a_{12} & a_{13} \\\\ a_{21} & a_{22} & a_{23} \\\\ a_{31} & a_{32} & a_{33} \\end{bmatrix}\\) is a square matrix of order 3,<\/p>\n
then \\(a_{11}(a_{22}a_{33} – a_{23}a_{a32})\\) – \\(a_{12}(a_{33}a_{21} – a_{23}a_{31})\\) + \\(a_{13}(a_{32}a_{21} – a_{22}a_{31})\\) = 0 is defined as the determinant of A.<\/p>\n
i.e.\u00a0 | A | = \\(a_{11}\\begin{vmatrix} a_{22} & a_{23} \\\\ a_{32} & a_{33} \\end{vmatrix}\\) – \\(a_{12}\\begin{vmatrix} a_{21} & a_{23} \\\\ a_{31} & a_{33} \\end{vmatrix}\\) + \\(a_{13}\\begin{vmatrix} a_{21} & a_{22} \\\\ a_{31} & a_{32} \\end{vmatrix}\\)<\/p>\n
Example 1<\/span><\/strong> : find the determinant of A = \\(\\begin{bmatrix} 3 & -2 & 4 \\\\ 1 & 2 & 1 \\\\ 0 & 1 & -1 \\end{bmatrix}\\).<\/p>\n Solution <\/span><\/strong>: | A | = \\(\\begin{vmatrix} 3 & -2 & 4 \\\\ 1 & 2 & 1 \\\\ 0 & 1 & -1 \\end{vmatrix}\\)<\/p>\n \\(\\implies\\) | A | = \\(3\\begin{vmatrix} 2 & 1 \\\\ 1 & -1 \\end{vmatrix}\\) – \\((-2)\\begin{vmatrix} 1 & 1 \\\\ 0 & -1 \\end{vmatrix}\\) + \\(4\\begin{vmatrix} 1 & 2 \\\\ 0 & 1 \\end{vmatrix}\\)<\/p>\n \\(\\implies\\) | A | = 3(-2 – 1) + 2(-1 – 0) + 4(1 – 0)\u00a0<\/p>\n = -9 – 2 + 4 = -7<\/p>\n Example 2<\/span><\/strong> : find the determinant of A = \\(\\begin{bmatrix} 1 & 2 & 3 \\\\ -4 & 3 & 6 \\\\ 2 & -7 & 9 \\end{bmatrix}\\).<\/p>\n Solution <\/span><\/strong>:\u00a0 | A | = \\(\\begin{vmatrix} 1 & 2 & 3 \\\\ -4 & 3 & 6 \\\\ 2 & -7 & 9 \\end{vmatrix}\\)<\/p>\n \\(\\implies\\) | A | = \\(1\\begin{vmatrix} 3 & 6 \\\\ -7 & 9 \\end{vmatrix}\\) – \\(2\\begin{vmatrix} -4 & 6 \\\\ 2 & 9 \\end{vmatrix}\\) + \\(3\\begin{vmatrix} -4 & 3 \\\\ 2 & -7 \\end{vmatrix}\\)<\/p>\n \\(\\implies\\) | A | = (27 + 42) – 2(-36 – 12) + 3(28 – 6) = 231<\/p>\n Note :<\/strong><\/p>\n (1) Only square matrices have their determinants. The matrices which are not square do not have determinants.<\/p>\n (2) The determinant of a square matrix of order 3 can be expanded along any row or column.<\/p>\n (3) If a row or a column of a determinant consist of all zeros, then the value of the determinant is zero.<\/p>\n\n\n