( adj. A) (adjA)=(cofA)′ cof of A11=12−2=10 cof of A12=−(16−1)=−15 cof of A13=8−3=5 cof of A21=−(12−8)=−4 cof of A22=(8−4)=4 cof of A23=−(4−3)=−1 cof of A31=(3−12)=−9 cof of A32=−(2−16)=14 cof of A33=(6−12)=−6 cof A=[