Answer
The required value is $\left( x-3 \right)\left( x-6 \right)$.
Work Step by Step
Consider the expression,
${{x}^{2}}-9x+18$
The given expression can be evaluated as:
$\begin{align}
& {{x}^{2}}-9x+18={{x}^{2}}-3x-6x+18 \\
& =x\left( x-3 \right)-6\left( x-3 \right) \\
& =\left( x-3 \right)\left( x-6 \right)
\end{align}$
Therefore, the value of ${{x}^{2}}-9x+18$ is $\left( x-3 \right)\left( x-6 \right)$.
