Question 16
Prove that $$
0 \leq y z + z x + x y - 2 x y z \leq \frac{7}{27}
$$ where $x$, $y$, $z$ are nonnegative real numbers that meet $x + y + z = 1$.
0 \leq y z + z x + x y - 2 x y z \leq \frac{7}{27}
$$ where $x$, $y$, $z$ are nonnegative real numbers that meet $x + y + z = 1$.