Giải thích các bước giải:
\[\begin{array}{l}
d,\\
{\left( {x + 1} \right)^2}\ge 0\\
\Rightarrow 3 - {\left( {x + 1} \right)^2} \le 3\\
\Rightarrow A \le 3\\
\Rightarrow {A_{\max }} = 3 \Leftrightarrow x{\rm{ }} + {\rm{ }}1 = 0\\
\Leftrightarrow x = - 1\\
e,\\
E = - \left| {0,1 + x} \right| - 1,9\\
E = - \left( {\left| {0,1 + x} \right| + 1,9} \right)\\
\left| {0,1 + x} \right| \ge0 \Rightarrow \left| {0,1 + x} \right| + 1,9 \ge1,9\\
\Rightarrow E \le- 1,9\\
\Rightarrow {E_{\max }} = - 1,9 \Leftrightarrow 0,1 + x = 0\\
\Leftrightarrow x = - 0,1\\
f,\\
\left| x \right| \geq0 \Rightarrow \left| x \right| + 2017\geq 2017\\
\Rightarrow F = \dfrac{1}{{\left| x \right| + 2017}} \le \dfrac{1}{{2017}}\\
\Rightarrow {F_{\max }} = \dfrac{1}{{2017}} \Leftrightarrow x = 0
\end{array}\]
