Đáp án:
Giải thích các bước giải:
Đặt $\frac{1}{2x-y}$ = a , $\frac{1}{x+y}$ = b
$\left \{ {{3a-6b=-1} \atop {a-b=0}} \right.$
⇔ $\left \{ {{3a-6b =-1} \atop {3a-3b=0}} \right.$
⇔ $\left \{ {{3b-6b=-1} \atop {a-b=0}} \right.$
⇔ $\left \{ {{-3b=-1} \atop {a-b=0}} \right.$
⇔ $\left \{ {{b=\frac{1}{3}} \atop {a=\frac{1}{3}}} \right.$
⇔ $\left \{ {{\frac{1}{2x-y}=\frac{1}{3}} \atop {\frac{1}{x+y}= \frac{1}{3} }} \right.$
⇔ $\left \{ {{2x-y=3} \atop {x+y=3}} \right.$
⇔ $\left \{ {{2x+x=3+3} \atop {x+y=3}} \right.$
⇔ $\left \{ {{3x=6} \atop {x+y=3}} \right.$
⇔ $\left \{ {{x=2} \atop {2+y=3}} \right.$
⇔ $\left \{ {{x=2} \atop {y=1}} \right.$
