## Elementary Linear Algebra 7th Edition

$E-2A$ is not defined. Because $A$ and $E$ have different sizes. Namely, the size of $A$ is $3\times 4$ and the size of $E$ is $4\times 3$.
$E-2A$ is not defined. Because $A$ and $E$ have different sizes. Namely, the size of $A$ is $3\times 4$ and the size of $E$ is $4\times 3$.