Answer :

Lilith
[tex]x^2 - 6x = -9\\\\x^2 - 6x +9=0\\ \\a=1, \ \ b=-6, \ \ c=9 \\\\ \Delta =b^2-4ac = (-6)^2 -4\cdot1\cdot 9 = 36 -36 =0 \\ \\x_{o}=\frac{-b }{2a}=\frac{ 6}{2 }=3[/tex]


MattD
[tex](a-b)^2=a^2-2ab+b^2[/tex] <--this is formula
[tex]x^2-6x+9=0[/tex]
[tex]x^2-(2*1*3)x+3^2=0[/tex] a=1,b=3
[tex](x-3)^2[/tex]