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Standard matrix addition and subtraction are defined for matching dimensions, because every position requires a corresponding entry. Different dimensions leave unmatched positions under this standard rule; a separately specified new convention would be a different operation.

Conditions: Matrices have different dimensions (e.g., one is 3x2 and the other is 2x2).

Standard matrix addition and subtraction are defined for matching dimensions, because every position requires a corresponding entry. Different dimensions leave unmatched positions under this standard rule; a separately specified new convention would be a different operation.

Conditions: Matrices have different dimensions (e.g., one is 3x2 and the other is 2x2).