[tex]$
\begin{array}{l}
f(x)=3x^2-2x-9 \\
g(x)=3x^3+2x^2-4x-9
\end{array}
$[/tex]

Find [tex]$(f-g)(x)$[/tex].

A. [tex]$3x^3 + x^2 - 2x - 18$[/tex]

B. [tex]$-3x^3 + x^2 + 2x$[/tex]

C. [tex]$3x^3 - x^2 - 2x$[/tex]

D. [tex]$3x^3 + 5x^2 - 6x - 18$[/tex]



Answer :

To solve the problem, which involves finding the difference between the functions [tex]\( f(x) \)[/tex] and [tex]\( g(x) \)[/tex], let's proceed with the following steps:

1. Write down the expressions for [tex]\( f(x) \)[/tex] and [tex]\( g(x) \)[/tex]:
[tex]\[ f(x) = 3x^2 - 2x - 9 \][/tex]
[tex]\[ g(x) = 3x^3 + 2x^2 - 4x - 9 \][/tex]

2. Find [tex]\( (f - g)(x) \)[/tex], which is [tex]\( f(x) - g(x) \)[/tex]:
[tex]\[ f(x) - g(x) = (3x^2 - 2x - 9) - (3x^3 + 2x^2 - 4x - 9) \][/tex]

3. Distribute the negative sign in front of [tex]\( g(x) \)[/tex] and combine like terms:
[tex]\[ f(x) - g(x) = 3x^2 - 2x - 9 - 3x^3 - 2x^2 + 4x + 9 \][/tex]

4. Combine like terms:
[tex]\[ f(x) - g(x) = -3x^3 + 3x^2 - 2x^2 - 2x + 4x - 9 + 9 \][/tex]
[tex]\[ f(x) - g(x) = -3x^3 + (3x^2 - 2x^2) + (-2x + 4x) + (-9 + 9) \][/tex]
[tex]\[ f(x) - g(x) = -3x^3 + x^2 + 2x \][/tex]

5. State the final result of [tex]\( (f - g)(x) \)[/tex]:
[tex]\[ (f - g)(x) = -3x^3 + x^2 + 2x \][/tex]

Therefore, the correct result of [tex]\( (f - g)(x) \)[/tex] is:
[tex]\[ \boxed{x(-3x^2 + x + 2)} \][/tex]

Among the provided options, this expression matches with:
[tex]\[ \boxed{-3x^3 + x^2 + 2x} \][/tex]