Question
Question: Let A be the set of all 3 × 3 symmetric matrix all of whose entries are either 0 or 1 five of these ...
Let A be the set of all 3 × 3 symmetric matrix all of whose entries are either 0 or 1 five of these entries are 1 and four of them are zero. Find the number of matrix in A are-
A
3
B
6
C
9
D
12
Answer
12
Explanation
Solution
3C1 + 3C1 . 3C2 = 3 + 3.3 = 3 + 9 = 12