matrice (mxp) * (3x3)=(1x3)
deci X (mxp) este tot (1,3)
adica X= (x y z)
inmultinmd obtinem sistemul
2x+3y+5z=1
3x+7y+4z=3
x+2y=-3
rezolvam ca la gimnaziu cu substitutia
x=-2y-3
primele 2 ercuatii devin
2(-2y-3)+3y+5z=1
3(-2y-3)+7y+4z=3
-y+5z=1+6=7
y+4z=3+9=12
9z=19
z=19/9
y=12-4z=12-76/9=108/9-76/9=32/9
x=-2y-3=-64/9-27/9=-91/9
verificare
2*(-91/9)+3*32/9+5*19/9=9/9=1
3(-91/9)+7*32/9 +4*19/9=27/9=3
-91/9+2*32/9=-27/9=-3
Verifica, sistemul este bine rezolvat
X= (-91/9 32/9 19/9) matrice linie
