MATEMATIKA 1 skripta studij: Biotehnologija i Prehrambena ... - PBF
MATEMATIKA 1 skripta studij: Biotehnologija i Prehrambena ... - PBF
MATEMATIKA 1 skripta studij: Biotehnologija i Prehrambena ... - PBF
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nastaje izbacivanjem njenog i-tog retka i j-tog stupca. Npr. ako je<br />
⎡<br />
⎤<br />
a 11 ... a 1,j−1 a 1j a 1,j+1 ··· a 1n<br />
. . . . .<br />
a i−1,1 ··· a i−1,j−1 a i−1,j a i−1,j+1 ··· a i−1,n<br />
A =<br />
a i,1 ··· a i,j−1 a ij a i,j+1 ··· a i,n<br />
,<br />
a i+1,1 ··· a i+1,j−1 a i+1,j a i+1,j+1 ··· a i+1,n<br />
⎢<br />
⎣ . . . . . ⎥<br />
⎦<br />
a n1 ··· a n,j−1 a nj a n,j+1 ··· a nn<br />
onda je<br />
⎡<br />
M ij =<br />
⎢<br />
⎣<br />
⎤<br />
a 11 ... a 1,j−1 a 1,j+1 ··· a 1n<br />
. . . .<br />
a i−1,1 ··· a i−1,j−1 a i−1,j+1 ··· a i−1,n<br />
a i+1,1 ··· a i+1,j−1 a i+1,j+1 ··· a .<br />
i+1,n<br />
. . . .<br />
⎥<br />
⎦<br />
a n1 ··· a n,j−1 a n,j+1 ··· a nn<br />
Minora elementa a ij matrice A ∈ M n,n je determinanta matrice M ij . Algebarski<br />
komplement elementa a ij je skalar A ij = (−1) i+j detM ij .<br />
Sada, za A ∈ M n,n vrijedi<br />
n∑<br />
detA = a ij A ij , 1 ≤ i ≤ n.<br />
j=1<br />
Ovu formulu nazivamo razvoj determinante po i-tom retku. Isto tako vrijedi<br />
formula Sada, za A = (a ij ) ∈ M n,n vrijedi<br />
n∑<br />
detA = a ij A ij , 1 ≤ j ≤ n<br />
i=1<br />
koju nazivamo razvoj determinante po j-tom stupcu.<br />
⎡ ⎤<br />
a 11 a 12 a 13 a 14<br />
Zadatak 9 A =<br />
a 21 a 22 a 23 a 24<br />
⎢<br />
⎣ a 31 a 32 a 33 a<br />
⎥<br />
34 ⎦ , M 23, A 23 , M 33 , A 33 =?<br />
a 41 a 42 a 43 a 44<br />
10