x-3y=2 & -2x+6y=-4 请问这个二元方程组的解有多少个解为0y=0,为什么说方程组有无数个解

（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 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 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) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 已知3x=4Y,5Y=6Z,求 (1)x:y:z;（2）x+y/y+z.请说明道理， 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= x-y/x+y=-1/2,x*x-xy-2y*y/x*x-3xy+2y*y的解是多少?同上,请将过程写出, x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 解二元一次方程组：3(x+y)-4(x-y)=4,x+y/2+x-y/6+1x+y/2+x-y/6+1=1 已知x²+4x+y²+6y+13=0,求x-y+(2y²/x+y) 请在10；20分前回答 4x=9y,求x+y/y;y-x/2x请给我完整过程 x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 2（x+y)-3(x-y)=3 ,4(x+y)+3(x-y)=15 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9