x+y=27 20y+xy=20x

x^2+xy+x=36,y^2+xy+y=20,求x+y. 有这样一道题,计算：（x-y)[(x+y)(x+y)-xy]-(x-y)[(x-y)(x-y)+xy]的值,其中x=20 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. xy+x=20 xy+y=18 .先化简,后计算.[2x(x²y-xy²)+xy(xy-x²)]/x²yx=20 已知实数x y满足x平方y+xy平方=20,xy+x+y=9,试求x^+y^的值. 已知实数x、y满足x²y+xy²=20,xy+x+y=9,求x²+y²的值. 解方程x*x+xy=y+y*y 已知x—xy=40,xy—y=—20,求代数式x—y和x+y—2xy的值 已知x-xy=40,xy-y=-20,求x-y和x+y-2xy的值.要有 过程,把你怎么想的写出来. 若x+y=9,xy=20则 x^2+y^2=_____, (x-y)^2=_____