y'=1/(xy+y^3)
已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y=
(x+2y-3xy)-(-2x-y+xy),其中x+y=1/2,xy=-1/2
已知3/(x-y)=1/xy 求(-x-2xy+y)/ (2x+3xy-2y)
实数xy满足y>=1 y
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
(x+2y-3xy+2x+y-xy)-(-2-y+xy),其中x+y=2分之1,xy=-2分之1
先化简,再求值 ⒈2(Xy+Xy)-3(Xy-xy)-4Xy,其中X=1,y=-1
xy/3x+2y=1/8 xy/2x+3y=1/7
已知x+y=3,xy=1,则4x+3xy+4y=