x ,y, z.>0 4x+3y+5z=1 求1/x+y + 1/y+z + 1/z+x 的最小值
【1/(x+y)+1/(y+z)+1/(x+z)】(4x+3y+5z)
=【1/(x+y)+1/(y+z)+1/(x+z)】【(x+y)+(2y+2z)+(3x+3z)】
≥(1+√2+√3)^2
所以1/(x+y)+1/(y+z)+1/(x+z)的最小值为(1+√2+√3)^2