we have
[tex] (x-12)(x+4)=9\\ x^{2} +4x-12x-48=9\\ x^{2} -8x-48=9 [/tex]
Group terms that contain the same variable, and move the constant to the opposite side of the equation
[tex] x^{2} -8x=9+48\\ x^{2} -8x=57 [/tex]
Complete the square. Remember to balance the equation by adding the same constants to each side
[tex] x^{2} -8x+16=57+16\\ x^{2} -8x+16=73 [/tex]
Rewrite as perfect squares
[tex] x^{2} -8x+16=73\\ (x-4)^{2} =73\\ (x-4)=(+/-)\sqrt{73} [/tex]
[tex] x1=4+\sqrt{73} \\ x2=4-\sqrt{73} [/tex]
therefore
the answer is
[tex] x1=4+\sqrt{73} \\ x2=4-\sqrt{73} [/tex]
