x+y=5000 x÷600+y÷200=15

x+y=5000 x÷600+y÷200=15 [(2x-y)(2x+y)+y(y-6x)]÷2x=? 先化简,再求值:y(x-y)-x(x+y)/x²-y²÷x²+y²/x+y,其中x=2,y=-1 2x-y=2,求[(x²+y²)-(x-y)²+2y(x-y)]÷4y 1-[(x-y)/(x+2y)]÷[(x+y)(x-y)/(x+2y)²] 1-[(x-y)/(x+2y)]÷[(x+y)(x-y)/(x+2y)²]= x²-4y² x+2y---------- ÷ --------分数线x²+2xy+y² x²+xyx²-4y² x+2y----------÷--------分数线x²+2xy+y² x²+xy(x+2y)(x-2y)x(x+y)=----------------(x+y)(x+y)(x+2y)(x-y)x=------(x+y)这样对了吗? 化简3x-2/(x+y)[(x+y)/3x-x-y]÷(x-y)/x [(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y [(x+y)(x-y)-(x-y)²+2y(x-y)]÷4y 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 [x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013先化简。在求值 [x／（x-y）]·[y²／（x+y）]-[x^4y／（x^4-y^4）]÷[x²／（x²+y²）]= 【（x+2y)（x-2Y)-(x-2y)²】÷4Y,其中x=2,y=½ 【（x+y)²-（x+y）（x-y)】÷2y其中x=-2011y=2012 (x+y)(x-y)+(x-y)^2-(6x^2×y÷2y-2xy^2÷2y)其中x=-3,y=1/3 (x+y)²-（x³+y³)÷（x+y) 计算：(x-y)^8÷(y-x)^4×(x-y) (x+y)²-(x³+y³)÷(x+y)