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-- Mathematics - Section B1
Matrices
If $A^3 =O$, then $I + A+ A^2$ equals
$I-A$
$(I-A)^{-1}$
$(I+A)^{-1}$
none of these
We have,
$(I-A) (I + A+ A^2)=I+A+ A^2-A-A^2-A^3 = I-O =I$
$∴(I-A)^{-1}=I+ A+ A^2$