Question

x² - 6x + 9 -y² 

Answer 1

$x^2-6x+9-y^2\\ =\left(x-3\right)^2-y^2\\ =\left(x-3-y\right)\left(x-3+y\right)$

Answer 2

\(x^2-6x+9-y^2\)

\(=\left(x^2-2.x.3+3^2\right)-y^2\)

\(=\left(x-3\right)^2-y^2\)

\(=\left(x-3-y\right)\left(x-3+y\right)\)

\(=\left(x-y-3\right)\left(x+y-3\right)\)

Answer 3