MCQ
Matrix ${A_\lambda } = \left[ {\begin{array}{*{20}{c}}
  \lambda &{\lambda  - 1} \\ 
  {\lambda  - 1}&\lambda  
\end{array}} \right],\lambda  \in N$ then the value of $\left| {{A_1}} \right| + \left| {{A_2}} \right| + \left| {{A_3}} \right| + ....... + \left| {{A_{300}}} \right|$ is
  • A
    $(299)^2$
  • $(300)^2$
  • C
    $(150)^2$
  • D
    $(301)^2$

Answer

Correct option: B.
$(300)^2$
b
$\left| {{{\rm{A}}_\lambda }} \right| = \left| {\begin{array}{*{20}{c}}
\lambda &{\lambda  - 1}\\
{\lambda  - 1}&\lambda 
\end{array}} \right| = {\lambda ^2} - {[\lambda  - 1)^2}$

$ = 2\lambda  - 1$

$\therefore \left| {{{\rm{A}}_1}} \right| + \left| {{{\rm{A}}_2}} \right| + \left| {{{\rm{A}}_3}} \right| +  \ldots . + \left| {{{\rm{A}}_{300}}} \right|$

$=1+3^{2}+5+\ldots . .+599 $ 

$= \frac{300}{2}(1+599)=(300)^{2} $

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