\[x^{2} - 6x + 10 > 0\]
\[\left( x^{2} - 6x + 9 \right) + 1 > 0\]
\[(x - 3)^{2} + 1 > 0\]
\[(x - 3)^{2} \geq 0\ для\ любого\ x;\]
\[1 > 0 \Longrightarrow x^{2} - 6x + 10 > 0 \Longrightarrow\]
\[\Longrightarrow ч.т.д.\]