Cap´ıtulo 1 Matrizes e Sistemas Lineares
Cap´ıtulo 1 Matrizes e Sistemas Lineares
Cap´ıtulo 1 Matrizes e Sistemas Lineares
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28 CAPÍTULO 2. MATRIZ INVERSA E DETERMINANTES<br />
Exemplo:<br />
Seja A =<br />
Solução :<br />
⎡<br />
⎢<br />
⎣<br />
<br />
An×n<br />
1 2 3<br />
1 1 2<br />
0 1 2<br />
. In×n<br />
⎤<br />
<br />
→ Gauss − Jordan → <br />
⎥<br />
⎦ ,encontre A −1 caso exista.<br />
In×n<br />
. A −1<br />
A −1 ⎡<br />
⎤<br />
1 2 3 . 1 0 0<br />
⎢<br />
⎥<br />
⎢<br />
⎥<br />
= ⎢<br />
⎣ 1 1 2 . 0 1 0 ⎥<br />
⎦<br />
0 1 2 . 0 0 1<br />
L (1)<br />
2 = (−1)L (0)<br />
1 + L (0)<br />
⎡<br />
⎤<br />
1 2 3 . 1 0 0<br />
⎢<br />
⎥<br />
⎢<br />
⎥<br />
2 → ⎢<br />
⎣ 0 −1 −1 . −1 1 0 ⎥<br />
⎦<br />
0 1 2 . 0 0 1<br />
→ L (1)<br />
3 = L (1)<br />
2 + L (0)<br />
⎡<br />
⎤<br />
1 2 3 . 1 0 0<br />
⎢<br />
⎥<br />
⎢<br />
⎥<br />
3 = ⎢<br />
⎣ 0 −1 −1 . −1 1 0 ⎥<br />
⎦<br />
0 0 1 . −1 1 1<br />
p = 3 e n = 3 ⇐⇒ p = n.<br />
Então a inversa existe. Assim podemos prosseguir...<br />
⎡<br />
⎤<br />
1 2 3 . 1 0 0<br />
⎢<br />
⎥<br />
⎢<br />
⎥<br />
⎢<br />
⎣ 0 −1 −1 . −1 1 0 ⎥ → L(1)<br />
⎦ 1 = (−3)L<br />
0 0 1 . −1 1 1<br />
(1)<br />
3 + L (0)<br />
1 e L (2)<br />
2 = L (1)<br />
2 + L (1)<br />
3 →<br />
⎡<br />
⎤<br />
1 2 0 . 4 −3 −3<br />
⎢<br />
⎥<br />
⎢<br />
⎥<br />
⎢<br />
⎣ 0 −1 0 . −2 2 1 ⎥ → L(2)<br />
⎦ 1 = 2L<br />
0 0 1 . −1 1 1<br />
(2)<br />
2 + L (1)<br />
1 e L (3)<br />
2 = (−1)L (2)<br />
2 →