Matrices 1.1

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The characteristics equation of a matrix A is $ t^2−t−1=0 $, then

(a)  $A^{−1}$ does not exist (b)  $A^{−1}$exit but cannot be determined from the data

(c)  $A^{−1}=A+1$               (d)   $A^{−1}=A−1$

Answer is ( )

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