Đáp án:
d) x=-14
Giải thích các bước giải:
\(\begin{array}{l}
a) - 28 - 7\left| { - 3x + 15} \right| = - 70\\
\to 7\left| { - 3x + 15} \right| = 42\\
\to \left| { - 3x + 15} \right| = 6\\
\to \left[ \begin{array}{l}
- 3x + 15 = 6\\
- 3x + 15 = - 6
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = 3\\
x = - 7
\end{array} \right.\\
b)\left| {18 - 2\left| { - x + 5} \right|} \right| = 12\\
\to \left[ \begin{array}{l}
18 - 2\left| { - x + 5} \right| = 12\\
18 - 2\left| { - x + 5} \right| = - 12
\end{array} \right.\\
\to \left[ \begin{array}{l}
2\left| { - x + 5} \right| = 6\\
2\left| { - x + 5} \right| = 30
\end{array} \right.\\
\to \left[ \begin{array}{l}
\left| { - x + 5} \right| = 3\\
\left| { - x + 5} \right| = 15
\end{array} \right.\\
\to \left[ \begin{array}{l}
- x + 5 = 3\\
- x + 5 = - 3\\
- x + 5 = 15\\
- x + 5 = - 15
\end{array} \right. \to \left[ \begin{array}{l}
x = 2\\
x = 8\\
x = - 10\\
x = 20
\end{array} \right.\\
c)12 - 2\left( { - x + 3} \right) = - 38\\
\to 2\left( { - x + 3} \right) = 50\\
\to 3 - x = 25\\
\to x = - 22\\
d) - 20 + 3\left( {2x + 1} \right) = - 101\\
\to 3\left( {2x + 1} \right) = - 81\\
\to 2x + 1 = - 27\\
\to x = - 14
\end{array}\)
