1.4x-3y=6 2/y=12 2.y/5+x=4 3.xy-9y=4 3x+6y=4 4.x+y=9 x²+y²=6 是二元一次方程组的有（）

【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 12y(x-y)^2-8(x-y)^3=? 3x+y=2 -y/x+y=123x+y=2 （-y/x）+y=12 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x+y/3+x-y/2=6 4(x+y)-2(x-y)=40 2(x+y)-3(x-y)=1 6(x+y)+(x-y)=51 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? x+y/2+ x-y/2=6 2(x+y)-3x+3y=24 求X Y 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 用换元法解方程组 2分之x+y+3分之x-y=6 2(x+y)+(x-y)=12