若2x-3y-1=y-x-8=x+6,求2x-y的值.(要全过程,)

若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 若(-x+6):(x-y):(4x+y)=3:14:1,求x+y 若(-x+6):(x-y):(4x+y)=3:14:1,求x+y 若x*x+y*y=x+y-1/2,求x,y的值如题 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) x*y=6x-y=1求X Y是多少?X=3 Y=2 求公式! 求值域 1,y=(x+2)/(x*x+3x+6) 2,y=3x/(x*x+4) 2x+3y-1=y-x-8=x+6求2x-y的值 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+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? x*x+2x-y*y+6y-8=0,x+y不等于2,求x-y的值 若｜y+5｜+(5x+1)2=0,求-3(2x-y)-｛7x-[6x+2y-(10x-8y)]-x-2(3x-4y)｝的值 若|y+5|+(5x+1)^2=0,求代数式-3(2x-y)-{7x-[6x+2y-(10x-8y)]-x-2(3x-4y)}的值 若｜y+5｜+(5x+1)^2=0,求-3(2x-y)-｛7x-[6x+2y-(10x-8y)]-x-2(3x-4y)｝的值 若x-y=2(x+y),求代数式x-y/x+y+x+y/x-y求代数式 x+y分之x-y+x-y分之x+y 已知:y=ax的3次方+bx+3,当x=-1/2时,y=-7,试求x=1/2时,y的值