xy+x=20 xy+y=18
xy+x=20 xy+y=18
x-xy=40,xy-y= -20,求代数式x-y和x+y-2xy
已知:x-xy=40,xy-y=-20,求代数式x-y和x+y-2xy的值.
x^2+xy+x=36,y^2+xy+y=20,求x+y.
[(xy-2)(-xy-2)-4(xy-1)^2]除以(-xy),其中x=20,y=-25分之1
xy'=y+xy的
(-3x^y+2xy)-( )=4x^+xy
.先化简,后计算.[2x(x²y-xy²)+xy(xy-x²)]/x²yx=20
x+y分之一=5,xy+xy分之一=18,求y+x分之一=多少
X²+2xy+y²/xy乘x²-2xy+y²/xy+y²=
xy+x-y=18,x,y各等于几
先化简,再求值 ⒈2(Xy+Xy)-3(Xy-xy)-4Xy,其中X=1,y=-1