2/1(x2-y)+3/1(x-y2)+6/1(x2+y2)
已知实数x.y满足(x2+y2)(x2+y2-1)=2,求x2+y2的值
2x2+xy-3y2+x+4y-1因式分解
已知x2+4y2+x2y2-6xy+1=0,求 x4-y4/2x-y 乘 2xy-y2/xy-y2 除以(x2+y2/x
已知圆x2+y2-2x-2y+1=0求x2+y2的最大值
求圆x2+y2+2x-6y+1=0与圆x2+y2+2y-..
请求:二元函数求极限lim (x2+y2 )1/2-sin(x2+y2 )1/2(x,y→0) (x2+y2 )3/2请
先化简再求值:-(x2+y2)+[-3xy-(x2-y2)],其中x=-1,y=2.
已知2x+y=7,x2+y2=5,求(4x+2y)2-3x2-y2+2(1-y2)的值.
x(x-1)-(x2-y)=-3,求x2-y2-2xy的值
x(x-1)-(x2-y)=-3,求x2+y2-2xy的值
已知x(x-1)-(x2-y)=-3,求x2+y2-2xy的值
2010.09.已知x、y为实数,且(x2+y2)(x2+y2+1)=20,求x2+y2的值