1.-15=xy+y(y-1)/2*2
化简求值1.x^2+2xy+y^2/x^2-y^2除以x^2+xy/xy-y^2X=1Y=-2011
(x+2y-3xy)-(-2x-y+xy),其中x+y=1/2,xy=-1/2
已知:xy+x=-1,xy-y=-2.
已知3/(x-y)=1/xy 求(-x-2xy+y)/ (2x+3xy-2y)
已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y=
(x+y-2xy)(x+y-2)+(1-xy)²
求微分方程y'=(1+y^2)/xy的通解
(x+2y-3xy+2x+y-xy)-(-2-y+xy),其中x+y=2分之1,xy=-2分之1
已知:x-y=1,xy=-2.求:(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值
x-y=1,xy=2.求:(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值
若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值
.已知:x-y=1,xy=-2.求:(-2xy+2 x+3y)-(3xy+2y-2x)-(x+4y+xy)的值