已知x-xy=8,xy-y=-9,求x+y-2xy的值
y'+xy=x^3求微分
如果xy+x+y=6,试求自然数 xy
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.
xy=2010,x+y=2009,求x,y
已知xy^2=-2,求-xy(x^2y^5-xy^3-y)的值.
已知xy^2=-2 求-xy(x^2y^5-xy^3-y)
已知x^2-xy=5,xy-y^2=-3求3(x^2-xy)-xy+y^2
已知x+y=12,xy=9,求(x+3xy+y)/(xy+xy)的值
已知x^-xy=5,xy-y^=-3,求式子3(x^-xy)-xy+y^的值
x-xy=40,xy-y= -20,求代数式x-y和x+y-2xy