Question

estude o sinal das funcoes f(x)=2x+4.

Answer 1

Verificando os valores de x que fazem f(x) > 0:

$f(x)~\textgreater~0\\\\2x+4~\textgreater~0\\\\2x~\textgreater-4\\\\x~\textgreater~(-4)/2\\\\\boxed{\boxed{x~\textgreater-2}}$

Encontrando os valores de x que fazem f(x) ser negativa:

$f(x)~\textless~0\\\\2x+4~\textless~0\\\\2x~\textless-4\\\\x~\textless~(-4)/2\\\\\boxed{\boxed{x~\textless-2}}$
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Logo:

$\boxed{\boxed{f(x)~\textgreater~0~se~x~\textgreater-2}}\\\\\\\boxed{\boxed{f(x)\ \textless \ 0~se~x~\textless-2}}$