若(x+y-3)2+(x-y+5)2=0.则x2-y2的值是( )
若x2-y2=100,x+y=-25,则x-y的值是( )
已知2x+y=7,x2+y2=5,求(4x+2y)2-3x2-y2+2(1-y2)的值.
已知:x=3,y=-5,x2-2xy+y2/x2-y2的值是
x(x-1)-(x2-y)=-3,求x2+y2-2xy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
若实数x,y满足x2-2xy+y2+x-y-6=0,则x-y的值是( )
已知x和y满足2x+3y=5,则当x=4时,代数式3x2+12xy+y2的值是( )
已知x2+y2=20,x2+xy-2y2=2(x+2y),求x+y的值
已知x-y+1,X2+Y2=25 求(x+y)2和x2-xy+y2的值
实数x、y满足3x2+2y2=6x,则x2+y2的最大值为( )
若(x+y)2=25,(x-y)2=1,x2+y2的值是______.