Đáp án:
14) \(\left[ \begin{array}{l}
x = 5\\
x = - 5\\
x = - 4
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
1) - 21 - x + 14 = - 8\\
\to x = - 21 + 14 + 8\\
\to x = 1\\
2) - 16 - 3x = 16.5\\
\to 3x = - 16 - 16.5\\
\to 3x = - 96\\
\to x = - 32\\
3) - 8x = - 46 + 22\\
\to - 8x = - 24\\
\to x = 3\\
4)2\left( {x + 1} \right) = - 4 - 18\\
\to 2\left( {x + 1} \right) = - 22\\
\to x + 1 = - 11\\
5)25 + 4x = - 27\\
\to 4x = - 52\\
\to x = - 13\\
6)\left| x \right| - 25 = 37\\
\to \left| x \right| = 62\\
\to \left[ \begin{array}{l}
x = 62\\
x = - 62
\end{array} \right.\\
7) - 17 - \left| x \right| = 2.\left( { - 9} \right)\\
\to \left| x \right| = - 17 + 18\\
\to \left| x \right| = 1\\
\to \left[ \begin{array}{l}
x = 1\\
x = - 1
\end{array} \right.\\
8) - 3{x^2} = - 53 + 5\\
\to - 3{x^2} = - 48\\
\to {x^2} = 16\\
\to \left| x \right| = 4\\
\to \left[ \begin{array}{l}
x = 4\\
x = - 4
\end{array} \right.\\
9)21 + 2{x^3} = - 33\\
\to {x^3} = - 27\\
\to {x^3} = {\left( { - 3} \right)^3}\\
\to x = - 3\\
10){\left( {x + 2} \right)^3} = - 8\\
\to {\left( {x + 2} \right)^3} = {\left( { - 2} \right)^3}\\
\to x + 2 = - 2\\
\to x = - 4\\
11)3.{\left( { - 2} \right)^x} + 101 = 5\\
\to {\left( { - 2} \right)^x} = - 32\\
\to {\left( { - 2} \right)^x} = {\left( { - 2} \right)^5}\\
\to x = 5\\
12){\left( { - 5} \right)^x} + 25.{\left( { - 5} \right)^x} = 650\\
\to 26.{\left( { - 5} \right)^x} = 650\\
\to {\left( { - 5} \right)^x} = 25\\
\to {\left( { - 5} \right)^x} = {\left( { - 5} \right)^2}\\
\to x = 5\\
13)\left[ \begin{array}{l}
3x + 21 = 0\\
5\left| x \right| - 15 = 0
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = - 7\\
\left| x \right| = 3
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = - 7\\
x = 3\\
x = - 3
\end{array} \right.\\
14)\left[ \begin{array}{l}
{x^2} - 25 = 0\\
{x^3} + 64 = 0
\end{array} \right.\\
\to \left[ \begin{array}{l}
\left| x \right| = 5\\
{x^3} = {\left( { - 4} \right)^3}
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = 5\\
x = - 5\\
x = - 4
\end{array} \right.
\end{array}\)
