Given expression: [tex]-3x^2-12.[/tex]
Let us factor out Greatest Common Factor first.
Greatest Common Factor is -3 there.
Factoring out -3 there.
[tex]-3(x^2+4)[/tex]
4 could be written as [tex]-(2i)^2[/tex].
Therefore,
[tex]-3(x^2+4) = -3[x^2-(2i)^2][/tex]
Applying difference of the square identity [tex](a)^2-(b)^2 = (a-b)(a+b)[/tex], we get
[tex]-3[x^2-(2i)^2] = -3(x-2i)(x+2i)[/tex]
Distributing -3 in first parenthesis, we get
-3(x-2i)(x+2i) = (-3x+6i)(x+2i)
