A matrix P is called idempotent if P^2 = P. If P is idempotent and P =/= I show that det(P)=0.(adsbygoogle = window.adsbygoogle || []).push({});

I don't really know where to go with this but i have a feeling that it involves taking the det of each side.

det(P^2) = det(P)

det(P)det(P) = det(P)

where to from here if thats even the right step/method to take, or if its even right at all >_>

Thanks :)

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# Matrix Proof: Idempotent

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