若实数xy满足x2+y2=4求xy的最值
已知实数x,y满足x2+xy+y2=3,则x2-xy+y2的最小值
已知非零实数x,y满足:x2+xy-2y2=0,求(x2+3y+y2)/(x2+y2)的值
设正实数x,y满足x2-xy+y2=1,求x2-y2的最大值和最小值
设x,y为实数,且x2+xy+y2=1,求x2-xy+y2的值的范围
正数xy满足x2-y2=2xy,求x+y分之x-y的值
已知实数x、y满足x+y+xy=9,x2y+xy2=20,求x2+y2的值.
已知实数XY 满足X2+Y2=1,求Y+2/X+1的取值范围
已知实数x,y满足(x2)+(y2)-xy+2x-y+1=0,求x,y的值
已知实数x、y满足X2+y2-xy+2x-y+1=0,试求x、y的值
已知x2-xy=-3,2xy-y2=-8,求2x2+4xy-3y2的值.
若实数XY满足X2+Y2=1,则X-2Y的最大值为
设实数x,y满足x2+y2=1则 xy的取值范围是?