0＜x＜y,x+y=1∴0＜x＜1/2＜y＜1根据基本不等式x2+y2＞2xy（也可以根据(x-y)^2＞0推导出来）又2xy/x=2＞1,∴2xy＞x(x^2+y^2)/y=(1-2y+2y^2)/y=2y+1/y-2令t=2y+1/y-22y^2-(t+2)y+1=0有唯一解判别式(t+2)^2-4*2=0(t+2)...