A) 2
B) 1
C) 0
D) -1
Correct Answer: B
Solution :
The matrix is not invertible if \[\left| \,\begin{matrix} 1 & a & 2 \\ 1 & 2 & 5 \\ 2 & 1 & 1 \\ \end{matrix}\, \right|=0\] \[\Rightarrow \] \[1\,(2-5)-a(1-10)+2(1-4)=0\] \[\Rightarrow \] \[-3+9a-6=0\Rightarrow a=1\].You need to login to perform this action.
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