To factor the given expression, find two numbers that their product is 9 and their sum is -6. Those are -3 and -3, the factored expression is:
[tex]\begin{gathered} w^2-6w+9=0 \\ (w-3)(w-3)=0 \\ (w-3)^2=0 \end{gathered}[/tex]Now, solve the equation for w:
[tex]\begin{gathered} (w-3)^2=0 \\ w-3=0 \\ w=3 \end{gathered}[/tex]w has a value of 3.