Calcular cada menor M_{ij} e o cofator C_{ij}=(-1)^{i+j}M_{ij}: M_{11}=1\cdot1-2\cdot2=-3, logo C_{11}=(-1)^{2}(-3)=-3; M_{12}=2\cdot1-2\cdot0=2, logo C_{12}=(-1)^{3}(2)=-2; M_{13}=2\cdot2-1\cdot0=4, logo C_{13}=(-1)^{4}(4)=4; M_{21}=2\cdot1-0\cdot2=2, logo C_{21}=(-1)^{3}(2)=-2; M_{22}=1\cdot1-0\cdot0=1, logo C_{22}=(-1)^{4}(1)=1; M_{23}=1\cdot2-0\cdot2=2, logo C_{23}=(-1)^{5}(2)=-2; M_{31}=2\cdot2-0\cdot1=4, logo C_{31}=(-1)^{4}(4)=4; M_{32}=1\cdot2-0\cdot2=2, logo C_{32}=(-1)^{5}(2)=-2; M_{33}=1\cdot1-2\cdot2=-3, logo C_{33}=(-1)^{6}(-3)=-3.
Passo 4
Montar a matriz de cofatores e obter a adjunta como sua transposta: