Question

If adj (A) = ⎡⎣⎢2−3−2−41202−72⎤⎦⎥ find A

Answer 1

∣A∣=∣∣∣∣∣∣∣∣−122−21−2−2−21∣∣∣∣∣∣∣∣=27

Adjoint of a matrix is the transpose of its' cofactor matrix. 

adj(A)=⎣⎢⎢⎡−3−6−663−66−63⎦⎥⎥⎤

A.adj(A)=⎣⎢⎢⎡−122−21−2−2−21⎦⎥⎥⎤×⎣⎢⎢⎡−3−6−663−66−63⎦⎥⎥⎤=⎣⎢⎢⎡27

Here we go ⚡

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