$\left \{ {{2x-3y=1} \atop {x+2y=4}} \right.$ ⇔ $\left \{ {{2x-3y=1} \atop {x=4-2y}} \right.$ ⇔ $\left \{ {{2.(4-2y)-3y=1} \atop {x=4-2y}} \right.$ ⇔ $\left \{ {{y=1} \atop {x=2}} \right.$ Bình luận
$\left \{ {{2x-3y=1} \atop {x+2y=4}} \right.$
⇔ $\left \{ {{2x-3y=1} \atop {x=4-2y}} \right.$
⇔ $\left \{ {{2.(4-2y)-3y=1} \atop {x=4-2y}} \right.$
⇔ $\left \{ {{y=1} \atop {x=2}} \right.$
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