Resposta :
[tex]\boxed{\frac{x^2-6x+9}{x^2-9}=\frac{(x-3)(x-3)}{(x+3)(x-3)}=\frac{x-3}{x+3}}[/tex]
x²-6x+9
x²-9
(x - 3)^2 = (x-3)(x-3) ==> (x-3)
(x+3)(x-3) (x+3)(x-3) (x+3)