若3x-y=7 则 -6x+2y-3=..,.,.,.,.,.,.,.,.,.,.,tongshang

若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 若2x=3y,则(x*x+y*y)/x*x=? 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5x+3y=3x+4y=x+2y+6,则x+y=___ 若x+3y=3x+2y=7,则x+y=几? 若x^2-y^2=6 x+y=3 则x-y=多少 若2x+2y=6x-3y,则x比y= 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 若7x+6(x-y)=-4,3x-4(y-x)=18,则x-y=__ 若3x=7y,则y比x= ,x:（x+y）= 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 3x+5y-(x+y)=6 2(x+y)-3x=-7 若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) 已知方程组{(X+Y)-3(X-Y)=7,2(X+Y)+(X-Y）=-7}则(X+Y)(X-Y)= 若x+2y分之x-y=3,则代数式x+2y分之2（x-y)-3(x-y)分之x+2y的值为 若x+y=4,则多项式1/2(x+y)+4(x-y)-3（x-y）-3/2(x+y)-x+y值是（）