化简:(x2+y2)+(2y2-x2)=______.
已知:(x2+y2+1)2-4=0,则x2+y2=______.
因式分解:(x2+2x+1)-y2=______.
已知实数x、y满足(x2+y2)(x2+y2-1)=2,则x2+y2的值为______.
已知x2+4x+y2-2y+5=0,则x2+y2=______.
设L为圆周x2+y2=a2,则∮L(x2+y2)ds=______.
已知(x2+y2)(x2+y2-6)+9=0,求x2+y2的值.
已知(x2+y2)(x2-1+y2)-12=0,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
多项式2(x2-3xy-y2)-(x2+2mxy+2y2)中不含xy项,则m=______.
如果x2+xy=2,xy+y2=-1,则x2-y2=______,x2+2xy+y2=______.
(选做题)已知x+2y=1,则x2+y2的最小值是______.