# JEE-Mains 2015 (4/30)

Algebra Level 4

$A=\left[ \begin{matrix} 1 & 2 & 2 \\ 2 & 1 & -2 \\ a & 2 & b \end{matrix} \right]$ If $$A$$ is a matrix satisfying the equation $$AA^T=9I$$, where $$I$$ is $$3 \times 3$$ identity matrix, then the ordered pair $$(a,b)$$ is equal to :

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