若x2-3xy-4y2=0,则x/y

若x2-3xy-4y2=0,则x/y 若2x+y=0则(x2+xy+y2)/(2xy-x2)的值 已知实数x,y满足x2+xy+y2=3,则x2-xy+y2的最小值 若X2+xy-2y2=0,则（x2+3xy+y2)/x2+y2=? 若x-y/x+y=2,则x2+2xy+y2/4xy=多少 解方程组 ｛3x2-y2=8 {4x2+12xy+9y2=1 {x2+2xy+y2-4=0 x2+xy+y2=4 4x2-9y2=0 x2-2xy+y2-1=0还有{x2+y2=4xy-y2+4=0x2-----x的平方 y2------y的平方 还有{2x-3y=12x2-3xy+y2-4x+3y-3=0 若|x-y|+（y+3）2=0,则x2+y2-2xy= x2-4y2-3xy+y+x 已知x2+4y2+x2y2+1=6xy,则(x4-y4)/(2x2+xy-y2)*(2x-y)/(xy-y2)/(x2+y2/y)2= 若xy+yz+zx=0,则3xy+x2(y+z)+y2(z+x)+z2(x+y)等于多少 若x2+xy-2y2=0,则(x2+3xy+y2)／(x2+y2)=?那假设x或y=o.那X Y就不能删掉啦.怎么办? 若x2-xy-2y2=0,Xy不等于0,则X/Y=? 若X2+Y2-2X-6Y+10=0 ,求（x2-y2)/xy的值 已知x2+y2+4x-2y+5=0,求x2+2xy+y2值 1.已知正数x,y满足x2-y2=2xy,求(x-y)/(x+y)的值2.若x2+xy-2y2=0则(x2+3xy-2y2)/x2-2y2)=_________3.先化简,后求值：(3-x)/(x-2)除以（x+2-2/(x-2)）,其中x=2√2  x的平方+ xy-2y的平方=0,则(X2+3Xy+Y2)/(X2+Y2)=__x的平方+ xy-2y的平方=0,则(X2+3Xy+Y2)/(X2+Y2)=__其中(X2+3Xy+Y2)/(X2+Y2)=__的2为平方 计算(x+y/x-y + 4xy/y2-x2)(x2-9y2)/（x2+2xy-3y2） 已知X2+3xy-4y2=0,求(x-y)÷(x+y)的值