If x = y = z, then $$\frac{{{{\left( {x + y + z} \right)}^2}}}{{{x^2} + {y^2} + {z^2}}}$$   is?

$$\eqalign{ & \frac{{{{\left( {x + y + z} \right)}^2}}}{{{x^2} + {y^2} + {z^2}}} \cr & {\text{Assume }}x = y = z = 1 \cr & \Leftrightarrow \frac{{{{\left( {1 + 1 + 1} \right)}^2}}}{{1 + 1 + 1}} \cr & \Leftrightarrow \frac{9}{3} \cr & \Leftrightarrow 3 \cr} $$