In \(P\) and \(Q\) are square matrices such that \(P^{2006}=0\) and \(P Q=P+Q\), then…
In \(P\) and \(Q\) are square matrices such that \(P^{2006}=0\) and \(P Q=P+Q\), then \(\operatorname{det}(Q)\) will be
- 0
- 1 only
- -1 only
- \pm 1
Solution
\(\begin{array}{llll}
& P^{2006} =O \text { and } P Q=P+Q \\
\Rightarrow & P^{2006} Q =P^{2006}+Q \cdot P^{2005} \\
\Rightarrow & O =O+Q \cdot P^{2005} \\
\Rightarrow & P^{2005} \cdot Q =O \\
\Rightarrow & \operatorname{det} \cdot\left(P^{2005} \cdot Q\right) =O \\
\Rightarrow & \operatorname{det} P^{2005}(\operatorname{det} Q) =O \Rightarrow \operatorname{det} Q=O
\end{array}\)
Asked in: AP EAMCET 2020 (17 Sep Shift 1)
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