Đáp án:
\(\begin{array}{l}
B2:\\
a)2 \ge x \ge - 2\\
b)\left[ \begin{array}{l}
x \ge 1\\
x \le - 1
\end{array} \right.\\
c)\left[ \begin{array}{l}
x \ge \sqrt 3 \\
x \le - \sqrt 3
\end{array} \right.\\
B3:\\
a)x = 36\\
b)x = 4\\
c)\left[ \begin{array}{l}
x = 5\\
x = - 5
\end{array} \right.\\
d)\left[ \begin{array}{l}
x = \sqrt 6 \\
x = - \sqrt 6
\end{array} \right.
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
B2:\\
a)DK:4 - {x^2} \ge 0\\
\to 4 \ge x\\
\to 2 \ge x \ge - 2\\
b)DK:{x^2} - 1 \ge 0 \to {x^2} \ge 1\\
\to \left[ \begin{array}{l}
x \ge 1\\
x \le - 1
\end{array} \right.\\
c)DK:{x^2} - 3 \ge 0\\
\to {x^2} \ge 3\\
\to \left[ \begin{array}{l}
x \ge \sqrt 3 \\
x \le - \sqrt 3
\end{array} \right.\\
B3:\\
a)DK:x \ge 0\\
\sqrt x = 6\\
\to x = 36\\
b)DK:x \ge 0\\
\sqrt x - 2 = 0\\
\to \sqrt x = 2\\
\to x = 4\\
c){x^2} = 25\\
\to \left| x \right| = 5\\
\to \left[ \begin{array}{l}
x = 5\\
x = - 5
\end{array} \right.\\
d){x^2} - 6 = 0\\
\to {x^2} = 6\\
\to \left| x \right| = \sqrt 6 \\
\to \left[ \begin{array}{l}
x = \sqrt 6 \\
x = - \sqrt 6
\end{array} \right.
\end{array}\)
