Question

Rezolvati sistemul de ecuatii:

X-3Y=6
X+Y=2


X-Y=-1
2X+Y=7

Answer 1

x-3y=6=> x=3y+6
x+y=2=> x=2-y
2-y=3y+6
-4y=4
y=-1
x=3

x-y=-1=>y=x+1
2x+y=7=> y=7-2x
x+1=7-2x
3x=6
x=2
y=3

Answer 2

1) { X-3Y=6 /(-)
{ X+Y=2

-3Y -Y = 6-2
-4Y = 4
Y = - 1

X = 6+3×(-1)
X = 6+(-3)
X = 6-3
X = 3

{ X = 3 si Y = - 1


2) { X-Y=-1 /(+)
{ 2X+Y=7

3X = -1+7
3X = 6
X = 6:3
X = 2

Y = 7-2×2
Y = 7-4
Y = 3

{X = 2 si Y = 3