Question 62388
You were almost done, you forgot that when you take the square root of both sides of an equation it's +/- the other side.  All you would need, then is to add 3 to both sides.
3.  {{{-9(x-3)^2=-7}}}
{{{-9(x-3)^2/-9=-7/-9}}}
{{{(x-3)^2=7/9}}}
{{{sqrt((x-3)^2)=+-sqrt(7/9)}}}
{{{x-3=+-sqrt(7)/3}}}
{{{x-3+3=3+-sqrt(7)/3}}}
{{{x=3-sqrt(7)/3}}}  and {{{x=3+sqrt(7)/3}}} <---this is fine
{{{x=(9-sqrt(7))/3}}} and {{{x=(9+sqrt(7))/3}}} is also fine.
Happy Calculating!!!