Question

Rezolvati sistemul de ecuatie
2(x+3y)=5
-x-2y=6
Rezolvati sestemul de ecuatie prin 2 metode metoda substiitutiei si metoda reducerii
Multumesc

Answer 1

{2x+6y=5
{-x-2y=6
metoda substitutiei
-x-2y=6     (-1)
x+2y=-6
x=-6-2y
inlocuim in rel.2x+6y=5
2(-6-2y)+6y=5
-12-4y+6y=5
2y=5+12
y=17/2
x=-6-2y=-6-2·(17/2)=-6-17
x=-23

metoda reducerii
{2x+6y=5
{-x-2y=6           ·2

{2x+6y=5
{-2x-4y=12
  /     2y=17
y=17/2

-x-2·17/2=6
-x-17=6
-x=17+6
-x=23      (-1)
x=-23