Given:
[tex]\begin{gathered} f(x)=\text{ x}^2\text{ + 3x} \\ g(x)\text{ = x + 2} \end{gathered}[/tex]
Required:
[tex](f\text{ .g\rparen\lparen4\rparen}[/tex]
Recall that:
[tex](f.g)(x)\text{ = f\lparen x\rparen. g\lparen x\rparen}[/tex]
Substituting we have:
[tex]\begin{gathered} (f.g)(x)=\text{ \lparen x}^2\text{ + 3x\rparen\lparen x+2\rparen} \\ (f.g)(4)\text{ = \lparen4}^2\text{ + 3\lparen4\rparen\rparen\lparen4 + 2\rparen} \\ =\text{ 28 }\times6\text{ } \\ =\text{ 168} \end{gathered}[/tex]
Answer: 168
