Đáp án:f)$\left \{ {{x=5} \atop {y=1}} \right.$
h)$\left \{ {{x=2} \atop {y=5}} \right.$
Giải thích các bước giải:
f)$\left \{ {{3(x-y)-y=11} \atop {x-2(x+5y)=-15}} \right.$ ⇔$\left \{ {{5x-5y-y=11} \atop {x-2x-10y=-15}} \right.$
⇔$\left \{ {{3x-4y=11} \atop {-x-10y=-15}} \right.$ ⇔$\left \{ {{3x-4y=11} \atop {-4x-4y=-60}} \right.$
⇔$\left \{ {{x=5} \atop {y=1}} \right.$
h)$\left \{ {{\frac{x+y}{3}+\frac{2}{3}=3} \atop {\frac{4x-y}{6}+\frac{x}{4}=1}} \right.$
⇔$\left \{ {{x+y+2=9} \atop {4(4x-y)+6x=24}} \right.$ ⇔$\left \{ {{x+y=7} \atop {22x-4y=24}} \right.$
⇔$\left \{ {{4x+4y=28} \atop {22x-4y=24}} \right.$ ⇔$\left \{ {{x=2} \atop {y=5}} \right.$
