Mathematics
State, with reason, whether the following are true or false. A, B and C are matrices of order 2 × 2.
(i) A + B = B + A
(ii) A - B = B - A
(iii) (B.C).A = B.(C.A)
(iv) (A + B).C = A.C + B.C
(v) A.(B - C) = A.B - A.C
(vi) (A - B).C = A.C - B.C
(vii) A2 - B2 = (A + B)(A - B)
(viii) (A - B)2 = A2 - 2A.B + B2.
Matrices
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Answer
(i) A + B = B + A
The above statement is true because addition of matrices is commutative.
(ii) A - B = B - A
The above statement is false because subtraction of matrices is not commutative.
(iii) (B.C).A = B.(C.A)
The above statement is true because multiplication of matrices is associative.
(iv) (A + B).C = A.C + B.C
The above statement is true because multiplication of matrices is distributive over addition.
(v) A.(B - C) = A.B - A.C
The above statement is true because multiplication of matrices is distributive over subtraction.
(vi) (A - B).C = A.C - B.C
The above statement is true because multiplication of matrices is distributive over subtraction.
(vii) A2 - B2 = (A + B)(A - B)
The above statement is false because laws of algebra for factorization and expansion are not applicable to matrices.
(viii) (A - B)2 = A2 - 2A.B + B2
The above statement is false because laws of algebra for factorization and expansion are not applicable to matrices.
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