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Home  >>  JEEMAIN and AIPMT  >>  Mathematics  >>  Class12  >>  Matrices
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If a matrix A is such that $3A^3+2A^2+5A+I=0$ then its inverse is

$\begin{array}{1 1}(A)\;-(3A^2+2A+5I)&(B)\;3A^2+2A+5I\\(C)\;3A^2-2A-5I&(D)\;\text{None of these}\end{array}$

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1 Answer

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$3A^3+2A^2+5A+I=0$
$I=-3A^3+2A^2+5A+I=0$
$IA^{-1}=-3A^2-2A-5I$
$A^{-1}=-(3A^2+2A+5I)$
Hence (A) is the correct answer.
answered Apr 23, 2014 by sreemathi.v
 
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