Răspuns:
a)
[tex]\left \{ {{3x-7y=-20} \atop {2x+3y=2}} \right. \\\\[/tex]
inmultim prima ecuatie cu -2 si a doua cu 3
[tex]\left \{ {{-6x+14y = 40} \atop {6x+9y=6}} \right. \\[/tex]
14y+9y=46
23y=46
y=2
2x+6=2
2x=-4
x=-2
b)
[tex]\left \{ {{5x+8y=13} \atop {-2x+3y=1}} \right.[/tex]
[tex]\left \{ {{10x+16y=26} \atop {-10x+15y=5}} \right.[/tex]
31y = 31
y=1
5x+8=13
x=1
f)
[tex]\left \{ {{x-6y=16} \atop {-2x+9y=-23}} \right. \\\left \{ {{2x-12y=32} \atop {-2x+9y=-23}} \right.[/tex]
-12y+9y=9
-3y=9
y=-3
x-6(-3)=16
x=16-18
x=-2
g)
[tex]\left \{ {{x+2y=5} \atop {3x-4y=-25}} \right. \\\left \{ {{-3x-6y=-15} \atop {3x-4y=-25}} \right.[/tex]
-6y-4y=-40
-10y=-40
y=4
x+8=5
x=-3
h)
[tex]\left \{ {{3x-4y=18} \atop {2x+5y=-11}} \right. \\\left \{ {{-6x+8y=-36} \atop {6x+15y=-33}} \right.[/tex]
8y+15y=-69
23y=69
y = 3
3x-12=18
3x=30
x=10
i)
[tex]\left \{ {{x-2(x+y)=3} \atop {y-3(x+y)=1}} \right. \\\left \{ {{-x-2y=3} \atop {-3x-2y=1}} \right. \\\left \{ {{3x-2y=-9} \atop {-3x-2y=1}} \right.[/tex]
-2y-2y=-8
-4y=-8
y=2
-x-4=3
-x=7
x=-7
Explicație pas cu pas:
