xy(y+y^2)-y^(xy-x)+2x(x^2-y^2)其中x=-2,y=2009
(x+2y-3xy)-(-2x-y+xy),其中x+y=1/2,xy=-1/2
(x+2y-3y)- (-2x-y+xy ) 其中x+y=0.5 xy等于-0.5
(x+2y-3xy)-(-2x-y+xy),其中x+y=,xy=-,求值.
已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值?
(xy-x^2)乘以(xy)/(x-y)
(x^2+xy/x-y)/(xy/x-y)计算
因式分解:x×x-xy-2y×y-x-y
先化简,再求值(x-y/x+y)^2÷(y-x/x^2+2xy+y^2)^2*1/x+y,其中x=-4,y=1
(x+2y-3xy+2x+y-xy)-(-2-y+xy),其中x+y=2分之1,xy=-2分之1
x^2+xy+x=36,y^2+xy+y=20,求x+y.
如果x^2+xy+y-14,y^@+xy+x=28,求x+y的值.
3(2x^y-3xy^2)-(xy^2-3x^2y),其中x+1/2,y=-1