Đáp án:
Giải thích các bước giải:
b2)
⇔3x-xy+4y-12=4
⇔x(3-y)+4(y-3)=4
⇔(x-4)(3-y)=4
xảy ra các trường hợp sau:
TH1\(\left[ \begin{array}{l}x-4=1\\3-y=4\end{array} \right.\) $\left \{ {{x=5} \atop {x=1}} \right.$
TH2:$\left \{ {{x-4=-1} \atop {3-y=-4}} \right.$ $\left \{ {{x=3} \atop {y=7}} \right.$
TH3:$\left \{ {{x-4=4} \atop {3-1=1}} \right.$ $\left \{ {{x=8} \atop {y=2}} \right.$
TH4:$\left \{ {{x-4=-4} \atop {3-y=-1}} \right.$ $\left \{ {{x=0} \atop {y=4}} \right.$
TH5: $\left \{ {{x-4=2} \atop {3-y=2}} \right.$ $\left \{ {{x=6} \atop {y=1}} \right.$
TH6: $\left \{ {{x-4=-2} \atop {3-y=-2}} \right.$ $\left \{ {{x=2} \atop {y=5}} \right.$
B3)
a=a+b-c+b+c-d
b=-a+b-c+a-b+d
c=a+b+a-b+c
d=-a-b+a+b+c
