已知:x^4-xy+y^4=1在（0,1）附近确定了函数y=y（x）,求y‘|（0.1）

已知xy>0,证明xy+xy/1+x/y+y/x>=4 已知xy大于0求证xy+1/xy+y/x+x/y大于等于4 已知/X-Y-1/+(XY+3)的平方=0,求(-2XY+2X+3Y)-(3XY+2Y-2X)-(X+4Y+XY)的值!已知/X-Y-1/+(XY+3)的平方=0,求(-2XY+2X+3Y)-(3XY+2Y-2X)-(X+4Y+XY)的值急! 已知X²+Y²+X²Y²-4XY+1=0 求:（X-Y)^2008-(XY)^2008 已知x^2+y^2+x^2y^2-4xy+1=0 求(x-y)^2008-(xy)^2008 已知|3-y|＋|x+y|=0,求[2(x+y)-3(xy+4)]÷1／xy的值. .已知:x-y=1,xy=-2.求:(-2xy+2 x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 已知x+y=3,xy=1,则4x+3xy+4y= 已知x y=1,xy=-3,求2xy-4x 4(y-2(xy-x)) 已知x²-3xy+4x=3,y²+xy-4y+7=0,则xy-1/2(x²+y²)的值为 已知（x+2)^2+|y+1|=0,求5xy^2-{2x^2y-[3xy^2-(4xy^2-2x^2y)]} 已知（x+2）*+|y+1|=0求5xy*-｛2x*y-【3xy*-（4xy*-2x*y）】｝的值 已知（x+2）*+|y+1|=0求5xy*-｛2x*y-【3xy*-（4xy*-2x*y）】｝的值帮忙啊!谢谢! 1.已知x+y=-4,xy=3,求5（2分之1xy+2y）+[6x-(2xy+y-3x)]的值2.已知（x+3）^2+|x-y+10|=0求代数式5x^2y-[2x^2y-(3xy-xy^2)-3x^2]-2xy^2-y^2的值 已知4x²+4xy+y²-4x-2y+1=0,求证2x²+3xy+y²-x-y=0 已知1/x-1/y=2,求3x+7xy-3y/2x-3xy-2y答案是1/x-1/y=2(y-x)/xy=2 得：x-y=-2xy(3x+7xy-3y)/(2x-3xy-2y)=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy)=xy/(-7xy)=-1/7 谁能帮我解释一下=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy) 是怎 已知x-y=3,xy=1,求（-2x+2x+3y)-(3xy+2y-2x)-(x+4y+xy) xy>0,证xy+1/xy+x/y+y/x>=4