Đáp án:
Tham khảo
Giải thích các bước giải:
1/$\left \{ {{2x+y=7} \atop {-x+4y=10}} \right.$
⇔$\left \{ {{2x+y=7} \atop {-2x+8y=20}} \right.$
⇔$\left \{ {{2x+y=7} \atop {9y=27}} \right.$
⇔$\left \{ {{x=2} \atop {y=3}} \right.$
2/$\left \{ {{4x-3y=-7} \atop {2x+5y=16}} \right.$
⇔$\left \{ {{4x-3y=-7} \atop {-4x-10y=-32}} \right.$
⇔$\left \{ {{4x-3y=-7} \atop {-13y=-39}} \right.$
⇔$\left \{ {{x=\frac{1}{2}} \atop {y=3}} \right.$
3/$\left \{ {{2x-3y=11} \atop {-4x+6y-5=0}} \right.$
⇔$\left \{ {{2x-3y=11} \atop {-4x+6y=5}} \right.$
⇔$\left \{ {{4x-6y=22} \atop {-4x+6y=5}} \right.$
⇔$\left \{ {{2x-3y=11} \atop {0=27(l)}} \right.$
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