x2+y2=x+y这个式子对不对?
将下列式子因式分解:x-x2-y+y2=______.
我做对了吗.x2(x-y)+y2(y-x)= x2(x-y)-y2(x-y)=x2-y2=(x+y)(x-y)
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)的值
4y2-(x2+y)+(x2-4y2),其中x=-28 y=
2010.09.已知x、y为实数,且(x2+y2)(x2+y2+1)=20,求x2+y2的值
已知x,y为实数,且(x2 +y2)(x2 +y2+2)=3.求x2 +y2的值
已知实数x.y满足(x2+y2)(x2+y2-1)=2,求x2+y2的值
x2-x-y2-y 解法:=(x2-y2)-(x+y) =(x+y)(x-y)-(x+y) =(x+y)(x-y-1)
解关于x,y的方程组{x2-y2+根号(x2+y2)=a xy=0
解方程组:y2=x3-3x2+2x;x2=y3-3y2+2y
已知:x=3,y=-5,x2-2xy+y2/x2-y2的值是
已知x2+4x+y2-2y+5=0,则x2+y2=______.