Respuesta :

Answer:

              [tex]\boxed{(x+2)^2-16=0}[/tex]

Step-by-step explanation:

[tex]{}\quad x^2\,+\,4x\ -\ 12=0\\\\\underbrace{x^2+2\cdot x\cdot2+2^2}-2^2-12=0\\\\{}\qquad(x+2)^2\ \ -4-12=0\\\\{}\qquad(x+2)^2-16=0[/tex]