1、化简或计算：（x-y+4xy/x-y）×（x+y-4xy/x-y）2、如图,A、B两个村庄分别位于小河的两侧,现准备在小河上修建一座桥,方便两村庄居民的交往,问桥修建在何处时,两村庄居民先走的路程最近?A.M N-

化简计算:[x-y+4xy/(x-y)] * [x+y-4xy/(x+y)] 【因式分解】计算 化简或求值 1.(x^2-y^2)(x^2+xy+y^2) / (x+y)(x^3-y^3)2.(x^2-4x+4)(3-x) / (2x-6)(x^2+x-6)3.已知 x+y=1,xy= -2,求(x^2+y^2+xy) / (x^2+y^2-xy) 的值4.已知（x^2+y^2）（x^2+y^2-1）=12,求x^2+y^2的值 计算或化简：[（x-y）/(x+3y)]÷[（x²-y²）/(x²+6xy+9y²)]-（2y）/x+y 计算或化简 (1)12xy/5a÷8x^2y (2)1- x-y/x+2y÷x^2-y^2/x^2+4xy+4y^2计算或化简(1)12xy/5a÷8x^2y (2)1- x-y/x+2y÷x^2-y^2/x^2+4xy+4y^2(3)(-ax^4y^3)÷(5/6ax^2y^2)=(4)(-2a^3b^2)^3÷(-3ab^3)^2=(5)3a/5xy=( )/10axy (a≠0)(6)a+2/a^2-4=1/( ) {[(x根号x)+(x根号y)]/(xy-y2)}-[x+(根号xy)+y]/[(x根号x)-(y根号y)] y2是指y的平方；求上述式子的值.{[(x根号x)+(x根号y)]/(xy-y2)}-[x+(根号xy)+y]/[(x根号x)-(y根号y)] 化简或计算。 整式的乘除,化简计算,1.-4x^3y*(1/2xy^2- 3xy)2.(x-y)^2-x(x-2y) 计算下面式子{x-y+[(4xy)/(x-y)]}{x-y-[(4xy)/(x-y)]} 计算:[x-y+4xy/(x-y)] * [x+y-4xy/(x+y)] 计算：（x-y+4xy/x-y)(x+y-4xy/x+y) (x-y+(4xy/x-y))(x+y-(4xy/x+y)) 分式计算 计算:2xy/(x+y)².(x+y)/4y 计算:(4xy(x-y)^-1+(x(y^-1)-(x^-1)y)/((x^-1)+(y^-1)))*(x+y)^-2 化简求值x-4y/2x-7xy+3y×x-2xy-3y/2x+3xy-2y÷3x-6y/4x-4xy+y,其中：x=1999,y=-1 计算：(xy-x²)×x-y/xy 计算:(x-2y)(1+x+2y+4y^2+2xy+x^2) 数学化简计算:(x+y)^2/xy-(x-y)^2/xy 计算3xy[2xy-x(y-2)+x-1] (x/x+y-x/y-x-2xy/x.x-y.y)/(1/x-1/y) 分式化简