I have not come across this kind of problem, hence, not sure:(adsbygoogle = window.adsbygoogle || []).push({});

A is nxn, such that A^2 + 3A + I =0

show that A is invertible and A^(-1) = -A-3I

So far I have this:

-A^2 - 3A = I

but now I am not sure if I can factor out A:

(-1)A [A + 3] = I

because I do not think that A + 3 is defined for matrices, since 3 is a scalar and not actually a vector.

Any hints are very much appreciated.

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