Let P be a matrix of order 3 × 3 such that all the entries in P are from the set - 1 ,   0,  …

Let P be a matrix of order 3×3 such that all the entries in P are from the set -1, 0, 1 . Then, the maximum possible value of the determinant of P is _______.

Solution

=a1a2a3b1b2b3c1c2c3=a1b2c3+a2b3c1+a3b1c2x-a3b2c1+a2b1c3+a1b3c2y
Now if x3 and y-3
The can be maximum 6 but it is not possible
because x=3 each term of x=1
And y=-3 each term of y=-1
i=13aibici=1  and i=13aibici=-1, which is a contradiction.
Now for value to be 5 one the terms must be zero but that will make two terms zero which means answer cannot be 5. Next possibility is 4 which can be obtained as 111-1111-11=11+1-1-1-1+11-1=4

Asked in: JEE Advanced 2018 (Paper 2)

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