X2+Y2=13 X+Y=15
1.已知X2+Y2-4X-6Y+13=0,求Y2-X2的值
已知x2-4x+y2-6y+13=0求x2+y2的值?
已知x2+y2+4x-6y+13=0 求x2-2x\x2+3y2
已知x2+y2+4x-6y+13=0
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
已知x2+y2-4x+6y+13=0,求x2-6xy+9y2的值.
x2-x-y2-y 解法:=(x2-y2)-(x+y) =(x+y)(x-y)-(x+y) =(x+y)(x-y-1)