If a matrix A has inverses B and C, then which one of the following is correct?
If a matrix A has inverses B and C, then which one of the following is correct? Correct Answer B should be equal to C
Concept:
If A, B, C are matrices then A(BC) = (AB)C
A-1 A = I
Calculations:
Given that, A has inverse B
⇒ AB = I = BA ....(1)
Also, A has inverse C.
⇒ AC = I = CA ....(2)
From (1) and (2),
AB = AC ....(3)
Pre multiply equation (3) by A-1
⇒A-1 (AB) = A-1 (AC)
⇒A-1 (AB) = A-1 (AC)
⇒(A-1 A)B = (A-1A)C
⇒(IB) = (IC)
⇒ B = C.
Hence, if a matrix A has inverses B and C,then B should be equal to C
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Feb 20, 2025