Answer
$A-B$ is a $ 2\times 3$ matrix
with all entries equal to zero.
Work Step by Step
If$ A$ and $B$ are $m\times n$ matrices,
then $A-B$ is the $m\times n$ matrix whose entries are given by:
$(A-B)_{ij}=A_{ij}-B_{ij}$
ijth entry of the difference $=$ difference of the ijth entries
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Since $A=B$, it follows that $A_{ij}=B_{ij},$ so
$(A-B)_{ij}=A_{ij}-B_{ij}=0$
$A-B$ is a $ 2\times 3$ matrix with all entries equal to zero.
