$\"\"$

The matrices are $\"\"$ , $\"\"$ , $\"\"$ and $\"\"$ .

Find $\"\"$ .

$\"\"$ (Original expression) \ \

$\"\"$ (Substitute $\"\"$ and $\"\"$ )

The matrix $\"\"$ has $\"\"$ row and $\"\"$ columns, so dimensions of matrix are $\"\"$ .

The dimensions of matrix are not equal.

The operation $\"\"$ is not impossible.

$\"\"$

The operation of $\"\"$ is impossible.