The matrix P is the inverse of a matrix Q. If I denotes the identity m...
Explanation:
To understand why option 'C' is the correct answer, let's first review the properties of matrix inverses.
Matrix Inverse:
The inverse of a square matrix Q, denoted as Q^(-1), is a matrix such that when it is multiplied by the original matrix Q, the result is the identity matrix I. In other words, Q^(-1) * Q = I.
Now, let's consider the given information that matrix P is the inverse of matrix Q.
Option Analysis:
a) PQ = I but QP ≠ I
This option suggests that PQ equals the identity matrix I, but QP is not equal to the identity matrix. However, this contradicts the definition of matrix inverses, as Q^(-1) * Q should equal I. Therefore, this option is incorrect.
b) QP = I but PQ ≠ I
This option suggests that QP equals the identity matrix I, but PQ is not equal to the identity matrix. Again, this contradicts the definition of matrix inverses, as Q^(-1) * Q should equal I. Therefore, this option is also incorrect.
c) PQ = I and QP = I
This option suggests that both PQ and QP are equal to the identity matrix I. This aligns with the definition of matrix inverses, as Q^(-1) * Q equals I. Therefore, this option is correct.
d) PQ * QP = I
This option suggests that the product of PQ and QP is equal to the identity matrix I. While matrix multiplication is associative, meaning (AB)C = A(BC), it is not necessarily commutative, meaning AB ≠ BA in general. Therefore, this option is incorrect.
Conclusion:
Based on the properties of matrix inverses, the correct answer is option 'c) PQ = I and QP = I'. This aligns with the definition of matrix inverses and ensures that both PQ and QP result in the identity matrix I.