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Determinants: 3×3 Determinants (page 2 of 2) Sections: 2×2 determinants, 3×3 determinants The computations for 3×3 determinants are messier than for 2×2's. Various methods can be used, but the simplest is probably the following: Copyright © Elizabeth Stapel 20042011 All Rights Reserved
Then det(A) = 1.
Then I add the downdiagonals, subtract the updiagonals, and simplify for the final answer: There are other methods for simplifying determinants by hand, and these other methods are required when evaluating larger determinants by hand, but those methods can probably wait until later. For the time being, note that your graphing calculator should be able to evaluate the determinant of any (square) matrix you enter. For instance: But make sure, even if you have a graphing calculator, that you can evaluate 2×2 and 3×3 determinants, because you are likely to have word problems where the determinants contain variables that your calculator can't handle. << Previous Top  1  2  Return to Index



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