A question about determinant

2012-08-28 4:18 am
Simplify the determinant
a+b__c___c
a___b+c__a
b____b__c+a
without direct expansion.

回答 (1)

2012-08-28 4:08 pm
✔ 最佳答案
= | 0 - 2b - 2a | (R1 - R2 - R3) to R1
| a b + c a |
| b b c + a |

= 2 | 0 - b - a |
| a b + c a |
| b b c + a |

= 2 | 0 0 - a | (C2 - C3 x b/a) to C2
| a (b + c) - b a |
| b b - b(c + a)/a c + a |

= - 2 a | a c |
| b - bc/a |

= - 2 a ( - bc - bc) = (-2a)(-2bc) = 4abc.


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