Question

Sejam $f$ e $g$ funções definidas em $R$ por $f(x)=2x+1$ e $g(x)=x-3$ o valor de $g[f(3)]$ é:

A) -1
B) 2
C) 3
D) 4

Answer 1

$\textit{Resolu\c{c}\~ao}\Rightarrow \left\{\begin{matrix} f(x)=2x+1\ e \ g(x)=x-3 & \\ f(3)=2.3+1 \\ f(3)=7 \\ g[f(3)] =g(7)\\ g(7)=7-3 \\ g(7)=4 \\ & \boxed{\boxed{d)4}}& \end{matrix}\right.$

Answer 2

$Resolu\c{c}\~ao\to \left\{\begin{array}{ccc}f(x) = 2x+1\\f(3) = 2*3+1 = 7\\\\g(x) = x-3\\\\g[(f(3)] = f(3)-3\\\\\boxed{\boxed{g[f(3)] = 7-3 = 4}}\to Letra\ D\end{array}\right$

Espero ter ajudado. :))