1/(2x+y)+4/(2x+3y) =1可化为：1/(2(x+y)-y)+4/(2(x+y)+y) = 1令m=2（x+y）可化为1/(m-y)+4/(m+y) = 1该函数可表示为一双曲线m+y + 4*(m-y) = m^2 - y^2m^2 - 5*m = y^2-3*ym^2-5*m+9/4 = (y-3/2)^2 >=0m^2 - 5*m +9...