Let M be any 3 × 3 matrix with entries from the set 0 , 1 , 2 . The maximum number of such matrices,…

Let M be any 3×3 matrix with entries from the set 0,1,2. The maximum number of such matrices, for which the sum of diagonal elements of MTM is seven, is______.

Solution

abcdefghiadgbehcfi

a2+b2+c2+d2+e2+f2+g2+h2+i2=7

Case-I : Seven 1's and two 0's

C29=36

Case-II: One 2 and three 1's and five 0's

9!5!3!=504

 Total =540

Asked in: JEE Main 2021 (24 Feb Shift 1)

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