有限数学 例

Two matrices can be multiplied if and only if the number of columns in the first matrix is equal to the number of rows in the second matrix. In this case, the first matrix is ${\displaystyle 3\times 2}$ and the second matrix is ${\displaystyle 2\times 3}$.

1番目の行列の各行と2番目の行列の各列を掛けます。

すべての式を掛けて、行列の各要素を簡約します。

Consider the corresponding sign chart.

The cofactor is the minor with the sign changed if the indices match a ${\displaystyle -}$ position on the sign chart.

The minor for ${\displaystyle a_{31}}$ is the determinant with row ${\displaystyle 3}$ and column ${\displaystyle 1}$ deleted.

Multiply element ${\displaystyle a_{31}}$ by its cofactor.

The minor for ${\displaystyle a_{32}}$ is the determinant with row ${\displaystyle 3}$ and column ${\displaystyle 2}$ deleted.

Multiply element ${\displaystyle a_{32}}$ by its cofactor.

The minor for ${\displaystyle a_{33}}$ is the determinant with row ${\displaystyle 3}$ and column ${\displaystyle 3}$ deleted.

Multiply element ${\displaystyle a_{33}}$ by its cofactor.

Add the terms together.

${\displaystyle 0}$と${\displaystyle 0}$をたし算します。

${\displaystyle 0}$と${\displaystyle 0}$をたし算します。