Answer:
[tex]18+81=9(x^{2}+6x+9)[/tex]
[tex]11=(x+3)^{2}[/tex]
Step-by-step explanation:
we have
[tex]0=9(x^{2} +6x)-18[/tex]
Adds 18 both sides
[tex]18=9(x^{2} +6x)[/tex]
Complete the square
[tex]18+81=9(x^{2}+6x+9)[/tex]
[tex]99=9(x^{2}+6x+9)[/tex]
Divide by 9 both sides
[tex]11=(x^{2}+6x+9)[/tex]
Rewrite as perfect squares
[tex]11=(x+3)^{2}[/tex]