已知x+2y=3则x=? x-y=7则y=?
已知{3x+2y=3 2x+3y=7 ,则x+y= ,x-y=
已知x/5=y/3,则(x/x+y)+(y/x-y)-(yxy/xxx-yxy)
若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于
已知:3x=7y,则x:y=------------------
已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
已知x*x+4x+y*y-2y+5=0,则x*x+y*y=?
已知1/x-1/y=3,则代数式x(2-7y)-y(7x+2)/x(1-y)-y(x+1)的值为多少.
已知x-2y/2x+3y=3/4,则x:y=
已知x-2y=3,则(2x+y-6)/(3x-y-9)=?
已知方程组{2x+y=7,x+2y=8,则x-y=(),x+y=().
已知x^2+y^2=25,x+y=7,且x大于y则x-y=