若x2+xy-2y2=0,则(x2+3xy+y2)/(x2+y2)=?
x2-y2=xy,xy不等于0求x2/y2=y2/x2
若x2+xy-2y2=0,则x
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)的值
若x<y<0,则x2−2xy+y2+x2+2xy+y2=( )
若x2+2xy-y2=7则x2+y2的最小值为
若X2+Y2-2X-6Y+10=0 ,求(x2-y2)/xy的值
已知X2次方+XY=3,XY+Y2次方=-2,求下例值:X2次方-Y2次方
已知实数x,y满足x2+xy+y2=3,则x2-xy+y2的最小值
已知x2+xy=3,xy+y2=-2,则2x2-xy-3y2=______.
已知x2+xy=3,xy+y2=-2,则2x2-xy-3y2的值为( )
如果M=3x2-2xy-4y2,N=4x2+5xy-y2,则8x2-13xy-15y2等于( )
解一个二元二次方程x2-4xy+3y2=0x2=10-y2