Matrices
Definition: A matrix is a rectangular array of numbers. The numbers in the array are called entries in the matrix. A matrix A with n rows and n columns is called a square matrix of order n, and the entries a11, a22, a33,...,ann are on the main diagonal of A.
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Two matrices are considered equal if they have the same size and the corresponding entries in the two matrices are equal.
Example 1:
Consider the matrices
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Here X does not equal Z since X and Z do not have the same size. For the same reason, Y does not equal Z. Also, X does not equal Y since not all the corresponding entries are equal.
A.5a