x-2y=-3 则5-2x+4y=?
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
已知x*x+4x+y*y-2y+5=0,则x*x+y*y=?
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1
若5x+3y=3x+4y=x+2y+6,则x+y=___
若x/y=4/3 则3x+2y/2x-5y=
已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(
数学题……555{(3x+y)(3x-y)-(x-5y)(5x-y)-(x-2y)²÷(-4x),x=-2.y
(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai
先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y
若2x-3y+4=0则x(x*x-1)+x(5-x*x)-6y+7
若3x-5y=0,则x+y/x=(),x-y/y=(),2x-3y/2x+3y=( )