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Determinants

Level 15 / mastery

3x3 mastery (+/-9)

3 visual steps / 3x3 signed cofactors

1. Signed line

1. Signed lineexpand row 1.-46-23-5781-3expand row 1combinecofactorsdet = 272
expand row 1.

expand row 1.

2. Signed term

2. Signed termcombine cofactors.-46-23-5781-3expand row 1combinecofactorsdet = 272
combine cofactors.

combine cofactors.

3. Determinant

3. Determinantdet = 272.DeterminantSettle signed terms.det = 272.combine cofactors
det = 272.

det = 272.

Practice Level 15

A few quick rounds make the products familiar; the sign is the only thing to guard.

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