1.{10x-2y=-2
{-5x+y=1
2.{3x-y=4
{2x+y=6
3.{x-2y=4
{2x-3y=1 giai he pt.e dg can gap .mn lm giup e vs
1.{10x-2y=-2
{-5x+y=1
2.{3x-y=4
{2x+y=6
3.{x-2y=4
{2x-3y=1 giai he pt.e dg can gap .mn lm giup e vs
1.$\left \{ {{10x-2y=-2} \atop {-5x+y=1}} \right.$
⇔$\left \{ {{10x-2y=-2} \atop {10x-2y=-2}} \right.$
⇔Vô số nghiệm
2.$\left \{ {{3x-y=4} \atop {2x+y=6}} \right.$
⇔$\left \{ {{-3x+y=-4} \atop {2x+y=6}} \right.$
⇔$\left \{ {{-5x=-10} \atop {2x+y=6}} \right.$
⇔$\left \{ {{x=2} \atop {2x+y=6}} \right.$
⇔$\left \{ {{x=2} \atop {2.2+y=6}} \right.$
⇔$\left \{ {{x=2} \atop {4+y=6}} \right.$
⇔$\left \{ {{x=2} \atop {y=2}} \right.$
3.$\left \{ {{x-2y=4} \atop {2x-3y=1}} \right.$
⇔$\left \{ {{2x-4y=8} \atop {2x-3y=1}} \right.$
⇔$\left \{ {{-y=7} \atop {2x-3y=1}} \right.$
⇔$\left \{ {{y=-7} \atop {2x-3y=1}} \right.$
⇔$\left \{ {{y=-7} \atop {2x-3.(-7)=1}} \right.$
⇔$\left \{ {{y=-7} \atop {2x+21=1}} \right.$
⇔$\left \{ {{y=-7} \atop {2x=-20}} \right.$
⇔$\left \{ {{y=-7} \atop {x=-10}} \right.$