Odpowiedź:
a)
[tex]\left \{ {{x+2y=8} \atop {2x-y=1}} \right.[/tex]
[tex]\left \{ {{x=8-2y} \atop {2*(8-2y)-y=1}} \right.[/tex]
[tex]\left \{ {{x=8-2y} \atop {16-4y-y=1}} \right.[/tex]
[tex]\left \{ {{x=8-2y} \atop {-5y=1-16}} \right.[/tex]
[tex]\left \{ {{x=8-2y} \atop {-5y=-15/:(-5)}} \right.[/tex]
[tex]\left \{ {{x=8-2*3} \atop {y=3}} \right.[/tex]
[tex]\left \{ {{x=2} \atop {y=3}} \right.[/tex]
(x,y)=(2,3)
b)
[tex]\left \{ {{x=2-3y} \atop {3(2-3y)-6y=-9}} \right.[/tex]
[tex]\left \{ {{x=2-3y} \atop {6-9y-6y=-9}} \right.[/tex]
[tex]\left \{ {{x=2-3y} \atop {-15y=-9-6}} \right.[/tex]
[tex]\left \{ {{x=2-3y} \atop {-15y=-15/:(-15)}} \right.[/tex]
[tex]\left \{ {{x=2-3*1} \atop {y=1}} \right.[/tex]
[tex]\left \{ {{x=-1} \atop {y=1}} \right.[/tex]
(x,y)=(-1,1)
c)
[tex]\left \{ {{y=-4+2x} \atop {x+2(-4+2x)=7}} \right.[/tex]
[tex]\left \{ {{y=-4+2x} \atop {x-8+4x=7}} \right.[/tex]
[tex]\left \{ {{y=-4+2x} \atop {5x=15/:5}} \right.[/tex]
[tex]\left \{ {{y=-4+6} \atop {x=3}} \right.[/tex]
[tex]\left \{ {{y=2} \atop {x=3}} \right.[/tex]
(x,y)=(3,2)
Szczegółowe wyjaśnienie:
