Giải thích các bước giải:
\(\begin{array}{l}
3.f(x) = \left\{ \begin{array}{l}
m - x;x < 0\\
x + m;x \ge 0
\end{array} \right.\\
Voi\;x < 0 \Rightarrow - x > 0 \Rightarrow f( - x) = m - ( - x) = x + m = f(x)\\
Voi\;x \ge 0 \Rightarrow - x < 0 \Rightarrow f( - x) = ( - x) + m = m - x = f(x)\\
\to Hso\;da\,cho\;la\;ham\;so\;chan\\
4.f(x) = \left\{ \begin{array}{l}
3x + 1;x > 0\\
0;x = 0\\
3x - 1;x < 0
\end{array} \right.\\
\;Voi\;x < 0 \Rightarrow - x > 0 \Rightarrow f( - x) = - 3x - 1 = - f(x)\\
Voi\;x > 0 \Rightarrow - x < 0 \Rightarrow f( - x) = - 3x + 1 = - f(x)\\
\Rightarrow Ham\,so\,le\\
5.f(x) = \left\{ \begin{array}{l}
5x + 3,x > 0\\
0\\
5x - 3,x < 0
\end{array} \right.\\
Voi\;x < 0 \Rightarrow - x > 0 \Rightarrow f( - x) = - 5x - 3 = - f(x)\\
Voi\;x > 0 \Rightarrow - x < 0 \Rightarrow f( - x) = - 5x + 3 = - f(x)\\
\Rightarrow Ham\,so\,le
\end{array}\)
