Mathematics · 2020
JEE Main · 8 January 2020, Shift 1 · Q72
The number of all 3 × 3 matrices A, with enteries from the set {-1,0,1} such that the sum of the diagonal elements of AA^T is 3, is \ \ \ \.
The number of all $\displaystyle 3 \times 3$ matrices A , with enteries from the set $\displaystyle \{-1,0,1\}$ such that the sum of the diagonal elements of $\displaystyle \mathrm{AA}^{\mathrm{T}}$ is $\displaystyle 3$, is \_\_\_\_.
Official answer
672
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