Let 𝐴 be a 3 × 3 real matrix with det(𝐴 + 𝑖 𝐼) = 0, where 𝑖 = √−1 and 𝐼 is the 3 × 3 identity matrix. If det(𝐴) = 3, then the trace of 𝐴2 is __________.
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