|（3A）^-1-2A*|=|1/3(A^-1)-2A*|=|1/3(A*/|A|)-2A*|=|2/3(A*)-2(A*)|=|-4/3(A*)|=(-4/3)^3|A*|=(-64/27)|A|^2=(-64/27)(1/4)=-16/27 答案补充 AA*=|A|E|A*|=|A|^n-1
