Answer:
Step-by-step explanation:
first one:
[tex]x^{2}+6x+9={(x+3)}^{2} \\\sqrt{{(x+3)}^{2} }=x+3[/tex]
second one:
[tex]x^{2}+6x+9=(x+3)^{2} \\\sqrt{(x+3)^{2} } = x+3[/tex]
third one:
[tex]x^{2} -6x+9=(x-3)^{2} \\\sqrt{(x-3)^{2} } =|x-3| \ \ (because \ x<-3)[/tex]
