Question Details

If A is a matrix and |A| ≠ 0, then solution of the equation XA = B is:

Options

A

X = A-1B

B

X =(1/|A| )B


C

X = BА-1


D

X = AB-1


Show Answer

Correct Answer :

Option C

X = BА-1


Solution :

The correct option is X = BA-1.

Let's understand how we arrive at this solution step-by-step.

We are given the matrix equation:
XA = B

We are also given that |A|0, which means that the matrix A is non-singular. Since A is non-singular, its multiplicative inverse, denoted as A-1, exists.

To solve for X, we need to isolate it. In matrix algebra, division is not defined, so we must multiply by the matrix inverse. Since matrix multiplication is non-commutative (meaning PQQP in general), the order of multiplication is extremely important.

In our equation XA = B, the matrix A is multiplied on the right side of X. Therefore, to eliminate A, we must post-multiply (multiply from the right) both sides of the equation by A-1:

(XA)A-1 = BA-1

Using the associative property of matrix multiplication, we can regroup the terms on the left-hand side:
X(AA-1) = BA-1

By definition, multiplying a matrix by its inverse yields the identity matrix, I (i.e., AA-1=I):
XI = BA-1

Since multiplying any matrix by the identity matrix leaves it unchanged (i.e., XI=X), we get:
X = BA-1

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