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Mathematics
Problem
Which one of the following statements about the identity matrix
I
n
I_n
I
n
is always true for every square matrix
A
A
A
of order
n
n
n
? a)
I
n
A
=
I
n
I_nA = I_n
I
n
A
=
I
n
b)
I
n
A
=
A
I_nA = A
I
n
A
=
A
c)
det
(
I
n
)
=
n
\det(I_n)=n
det
(
I
n
)
=
n
d)
I
n
I_n
I
n
is invertible only when
n
=
1
n=1
n
=
1
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