Let M be a 2 × 2 symmetric matrix with integer entries. Then M i...
X 3 matrix and N be a 3 x 2 matrix. We can find their product MN as follows:
MN = ⎡⎣⎢⎢∑k=1^3 m1,kn_k,1∑k=1^3 m1,kn_k,2∑k=1^3 m1,kn_k,3∑k=1^3 m2,kn_k,1∑k=1^3 m2,kn_k,2∑k=1^3 m2,kn_k,3⎤⎦⎥⎥
where m1,k and m2,k are the entries of M and n_k,1 and n_k,2 are the entries of N.
We can simplify this expression by using matrix multiplication rules:
MN = ⎡⎣⎢⎢∑k=1^3 m1,kn_k,1∑k=1^3 m1,kn_k,2∑k=1^3 m1,kn_k,3∑k=1^3 m2,kn_k,1∑k=1^3 m2,kn_k,2∑k=1^3 m2,kn_k,3⎤⎦⎥⎥
= ⎡⎣⎢⎢m1,1n_1,1 + m1,2n_2,1 + m1,3n_3,1 m1,1n_1,2 + m1,2n_2,2 + m1,3n_3,2 m1,1n_1,3 + m1,2n_2,3 + m1,3n_3,3 m2,1n_1,1 + m2,2n_2,1 + m2,3n_3,1 m2,1n_1,2 + m2,2n_2,2 + m2,3n_3,2 m2,1n_1,3 + m2,2n_2,3 + m2,3n_3,3⎤⎦⎥⎥
Therefore, the product MN is a 2 x 2 matrix.