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
  1. 0
  2. 1 only
  3. -1 only
  4. \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)

Practice more Matrices questions on Aicharya