Q37 / 75 · NTA Abhyas (JEE Main) 2020 · Mathematics · Matrices

The number of all possible symmetric matrices of order 3×3 with each entry 1 or 2 and whose sum of diagonal elements is equal to 5, is

Correct answer: 24

Solution

Since, trace is equal to 5⇒ diagonal elements are 1,2,2
∵ Matrix is also symmetric
Therefore, possible number of such matrices =3!2!×23=3×8=24

Hence, the correct answer is 24.

More Matrices Questions