有限数学示例

$- 3 A = [\begin{array}{c} - 5 & 2 \\ - 3 & 0 \end{array}]$

解题步骤 1

Consider the corresponding sign chart.

$[\begin{array}{c} + & - \\ - & + \end{array}]$

解题步骤 2

Use the sign chart and the given matrix to find the cofactor of each element.

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解题步骤 2.1

Calculate the minor for element $a_{11}$ .

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解题步骤 2.1.1

The minor for $a_{11}$ is the determinant with row $1$ and column $1$ deleted.

$| \begin{array}{c} 0 \end{array} |$

解题步骤 2.1.2

$1 \times 1$ 矩阵的行列式即为该元素本身。

$a_{11} = 0$

解题步骤 2.2

Calculate the minor for element $a_{12}$ .

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解题步骤 2.2.1

The minor for $a_{12}$ is the determinant with row $1$ and column $2$ deleted.

$| \begin{array}{c} - 3 \end{array} |$

解题步骤 2.2.2

$1 \times 1$ 矩阵的行列式即为该元素本身。

$a_{12} = - 3$

解题步骤 2.3

Calculate the minor for element $a_{21}$ .

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解题步骤 2.3.1

The minor for $a_{21}$ is the determinant with row $2$ and column $1$ deleted.

$| \begin{array}{c} 2 \end{array} |$

解题步骤 2.3.2

$1 \times 1$ 矩阵的行列式即为该元素本身。

$a_{21} = 2$

解题步骤 2.4

Calculate the minor for element $a_{22}$ .

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解题步骤 2.4.1

The minor for $a_{22}$ is the determinant with row $2$ and column $2$ deleted.

$| \begin{array}{c} - 5 \end{array} |$

解题步骤 2.4.2

$1 \times 1$ 矩阵的行列式即为该元素本身。

$a_{22} = - 5$

解题步骤 2.5

The cofactor matrix is a matrix of the minors with the sign changed for the elements in the $-$ positions on the sign chart.

$[\begin{array}{c} 0 & 3 \\ - 2 & - 5 \end{array}]$

解题步骤 3

Transpose the matrix by switching its rows to columns.

$[\begin{array}{c} 0 & - 2 \\ 3 & - 5 \end{array}]$

有限数学 示例

有限数学示例