Correct Answer - A
A
2
×
2
2
square matrix has 4 elements each of which can be chosen in 2 ways.
∴
∴
Total number of
2
×
2
2
square matrices with elements 1 and -1
2
4
=
16
2
.
Out of these 16 matrices, following matrices are singular :
[
1
1
−
1
−
1
]
,
[
−
1
−
1
1
1
]
,
[
1
1
1
1
]
,
[
−
1
−
1
−
1
−
1
]
[
[
−
1
1
1
1
]
,
[
1
−
1
1
−
1
]
,
[
1
−
1
−
1
1
]
,
[
−
1
1
1
−
1
]
[
∴
∴
Number of non-singular matrices =16-8=8.
Hence, required probability
=
8
16
=
1
2
=