当1≤x^2+y^2≤2时,x^2-xy+y^2的最大值和最小值是多少?

当x-y=2xy时,求4x-3xy-4y/xy 当x=2 y=2分之1 时,代数式(x+y)(x-y)+(x-y)^-(x^-3xy ) 当x+y=5xy时,（3x+xy+3y)/x-2xy+y=? 当1≤x^2+y^2≤2时,x^2-xy+y^2的最大值和最小值是多少? 当x+y=1,xy=-2,3x+3y-2xy过程 当x=2,y=1时,代数式x^4-xy^3-x^3y-3x^2y+3xy^2+y^4 当x=-2,y=1时x^-2xy+y^的值 当x-y=1时,求x^4-xy^3-x^3y-3x^2y+3xy^2+y^4的值 当x-y=1时,那么x^4-xy^3-x^3y-3x^2y+3xy^2+y^4的值是? 当x=2分之1,y=-4时(xy-x的平方)÷xy分之x-ygoodpeople 当x=3,y=3分之1时,求代数出3xy-[2xy-2(xy-2分之3xy)+xy]+3xy的值 当x=3,y=-1/3时求代数式3x*xy-[2xy*y-2(xy-2/3x*xy)+xy]+3xy*y的值 将x(x+y)(x-y)-x(x+y)2进行因式分解,并求当x+y=1007,xy=-1时此式的值 (xy/(x^2+y^2))^x当x,y都趋于正无穷时极限是多少? 当x=2008,y=2009时,求代数式(x-y)/x/(x-(2xy-y^2)/x) .(x+y-2)(x+y-2xy)+(xy-1)^2 当x=2,y=1÷2时,化简代数式(x+y)(x-y)+(x-y)²-(x²-3xy)的值 当x=2 y=2分1时 求代数式(x+y)(x-y)+(x-y)的平方-(x的平方-3xy)的值