sunt 2 metode:
1) metoda reducerii
{2x+3y=1
{2x-5y=9 ·(-1)⇒
{2x+3y=1
{-2x+5y=-9
/ 8y=-8
y=-8/8=-1
y=-1
din 2x+3y=1⇒2x+3·(-1)=1
2x-3=1
x=(1+3)/2
x=2
deci x=2 si y=-1
2) metoda substitutiei
x=(1-3y)/2 inlocuim in a II relatie
2(1-3y)/2-5y=9
1-3y-5y=9
-8y=9-1
-8y=8 ·(-1)
y=-8/8=-1
x=(1-3y)/2=(1-3·-1)/2=(1+3)/2=4/2
x=2
