Question 1184377
<pre>
{{{matrix(10,4,

x^3+y^3,"">="",xyz(x/z+y/z),"",
if,and, only, if,
(x+y)(x^2-xy+y^2),"">="",xy(x+y),"",
if,and, only, if,
x^2-xy+y^2,"">="",xy,"",
if,and, only, if,
x^2-2xy+y^2,"">="",0,"",
if,and, only, if,
(x-y)^2,"">="",0,"",
which,is, definitely, true)}}}

If you prefer, you can reverse the 
steps and omit the "if and only If"'s.

Edwin</pre>