已知0已知0已知0x>0,1-x>0y/2=x(1-x)<={[x+(1-x)]/2}^2=1/4y<=1/2所以最大值是1/2
已知0x>0,1-x>0y/2=x(1-x)<={[x+(1-x)]/2}^2=1/4y<=1/2所以最大值是1/2