We need to remember that:
[tex](f-g)(x)=f(x)-g(x)[/tex]
Then we have that:
[tex]\begin{gathered} (f-g)(x)=(3x^3+4x^2-6x-7)-(2x-4) \\ =3x^3+4x^2-6x-7-2x+4 \\ =3x^3+4x^2-8x-3 \end{gathered}[/tex]
Therefore:
[tex](f-g)(x)=3x^3+4x^2-8x-3[/tex]
and the answer is C.
