Respuesta :

serenavass

Step-by-step explanation:

(f-g)(x)=

[tex]x ^{2} - 3x + 9 - (3 {x}^{3} + 2 {x}^{2} - 4x - 9) = \\ x ^{2} - 3x + 9 - 3 {x}^{3} - 2 {x}^{2} + 4x + 9 = \\ - 3 {x}^{3} - x ^{2} + x + 18[/tex]