Matrices & Determinants · JEE Main previous year questions

2015 1 question

1. Q102015 · 4 Apr 2015 · Shift 1

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

   1. A.$(2,1)$
   2. B.$(-2,-1)$
   3. C.$(2,-1)$
   4. D.$(-2,1)$
   Show answer

   Answer: B