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Web skærmformat. - Aarhus Universitet

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V. Matricer – 4. Determinanter 422<br />

Kan skrives<br />

|A| = (−1) i+1 ai1|Ai1| + (−1) i+2 ai2|Ai2| + · · ·<br />

4.6. Determinant mange veje ☞ [LA] 8 Determinanter<br />

• Determinanten kan beregnes ved søjleudvikling<br />

n<br />

|A| =<br />

i=1<br />

(−1) i+j aij|Aij|<br />

• Determinanten er uafhængig af valgt række/søjle.<br />

• Eksempel ⎛<br />

1 2<br />

⎞<br />

3<br />

⎝4<br />

5 6⎠<br />

7 8 9<br />

12<br />

⎛<br />

− ∗<br />

⎞<br />

−<br />

= ⎝4<br />

| 6⎠<br />

=<br />

7 | 9<br />

<br />

4 6<br />

7 9<br />

4.7. Udregn determinant af orden 4 ☞ [LA] 8 Determinanter<br />

Eksempel 1<br />

<br />

<br />

1<br />

0 7 0<br />

<br />

<br />

0<br />

1 0 0<br />

<br />

<br />

0<br />

0 1 0<br />

= (−1)<br />

<br />

0<br />

0 0 1<br />

4+4<br />

<br />

<br />

1<br />

0 7<br />

<br />

<br />

0<br />

1 0<br />

<br />

0<br />

0 1

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