(x+3)*y=12 x*(y+2)=18 动脑筋

若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 12y(x-y)^2-8(x-y)^3=? (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 二元一次方程 ：2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 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 变量x,y满足约束条件,x+y>=3,x-y>=-1,2x-y (x-y)^2+(x+y)(x-y) 其中 X =3 Y=-1 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 3x+y=2 -y/x+y=123x+y=2 （-y/x）+y=12 {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? x+y+2(-x-y+1)=3(1-y-x)-4-(y+x-1),x+y=? 解方程组:(x+3)(y-2)=(x-3)(y+10),(x+1)(y+3)=(x-2)(y+12) 解方程：（x+3)(y-2)=(x-3)(y+10) (x-1)(y+3)=(x+2)(y+12) 解方程组{2(x-y)/3 - x+y/4=-1 6(x+y)-41(x-y)=12 4(x+2)=1-5y 4(x+y)-3(x-y)=12 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x)