x = 1, -4
Step-by-step explanation:
[tex]f(x) = g(x) \Rightarrow -x^2 - 3x + 12 = 2x^2 + 6x[/tex]
Collecting all similar terms, we get
[tex]3x^2 + 9x - 12 =0[/tex] or [tex]x^2 + 3x - 4 = 0[/tex]
This can then be factored as
[tex](x - 1)(x + 4) = 0[/tex]
So [tex]f(x) = g(x)[/tex] when [tex]x = 1[/tex] or [tex]x = -4.[/tex]
