ComplexNumberApplication
  
  
    GeometricInequality
  
  
    Intermediate
  
  
  Let positive real number $x$, $y$, and $z$ satisfy $x+y+z=1$. Find the minimal value of $u=\sqrt{x^2 + y^2 + xy} + \sqrt{y^2 +z^2 +yz} +\sqrt{z^2 +x^2 + xz}$
 
    
      The solution for this problem is available for 
$0.99.
      You can also purchase a pass for all available solutions for 
$99.