Not too good with an explanation, but when seeing the (x-2)^2, you understand that the highest power or the leading term should be [tex] x^{2} [/tex]. The power of the leading or the highest power would tell you how many solutions that equation has. For example, X + 3 = 0, has 1 solution, x^10 + 1 = 0 has 10 solutions.
[tex] (x - 2)^{2} - 40 = 9 [/tex]
[tex] (x - 2)(x-2) - 40 - 9 = 0 [/tex]
[tex] x^{2} - 4x + 4 - 49 = 0 [/tex]
[tex] x^{2} - 4x - 45 = 0 [/tex]
Use diamond or any type of factor that you learn
(x - 9)(x+5) = 0
x = 9 or x = -5
