已知x2-y2=4,那么(x-y)2(x+y)2=______.
已知x2+4x+y2-2y+5=0,则x2+y2=______.
已知x+y=4,x2+y2=10,则(x-y)2=______.
已知x-y=2,则x2-y2-4y=______.
(选做题)已知x+2y=1,则x2+y2的最小值是______.
已知x-y=5,(x+y)2=49,则x2+y2的值等于______.
已知实数x、y满足(x2+y2)(x2+y2-1)=2,则x2+y2的值为______.
已知x2-4y2=20,x+2y=5,则x=______,y=______.
已知x2+y2+5/4=2x+y,那么y-x=
已知2x+y=7,x2+y2=5,求(4x+2y)2-3x2-y2+2(1-y2)的值.
已知x+y=4,xy=2,则x2+y2+3xy=______.
已知xy=3,x2+xy-2y2=2(x+2y),且x≠-2y,则x+y=______.
已知x2+y2+z2-2x+4y-6z+14=0,则x+y+z=______.