2x+3y-1=y-x-8=x+6求2x-y的值

若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 求值域 1,y=(x+2)/(x*x+3x+6) 2,y=3x/(x*x+4) (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) x+y/2+ x-y/2=6 2(x+y)-3x+3y=24 求X Y 已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? x*x+2x-y*y+6y-8=0,x+y不等于2,求x-y的值 {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? x*y=6x-y=1求X Y是多少?X=3 Y=2 求公式! 2x+3y-1=y-x-8=x+6求2x-y的值 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 6x-2y=5 8x-3y=-5 求x,y 已知x-2y=2,求4x-y-8分之3x+y-6 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 x+y=8 2x-y=1 求3x+5y 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙