M1,1=(−1)1+1⋅(−5)=−5;M1,2=(−1)1+2⋅7=−7;M2,1=(−1)2+1⋅5=−5;M2,2=(−1)2+2⋅2=2;
Cofactor(A)=(M1,1M2,1M1,2M2,2) =(−5−5−72)
More explanations:
∣∣275−5∣∣ M1,1=(−1)1+1⋅(−5)=−5
∣∣275-5∣∣ M1,2=(−1)1+2⋅7=−7
∣∣275-5∣∣ M2,1=(−1)2+1⋅5=−5
∣∣275-5∣∣ M2,2=(−1)2+2⋅2=2;
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