Đáp án:
$\begin{array}{l}
a)\left( {19x + {{2.5}^2}} \right):14 = {\left( {13 - 8} \right)^2} - {4^2}\\
\Rightarrow \left( {19x + 50} \right):14 = {5^2} - 16\\
\Rightarrow \left( {19x + 50} \right):14 = 25 - 16 = 9\\
\Rightarrow 19x + 50 = 9 \times 14\\
\Rightarrow 19x + 50 = 126\\
\Rightarrow 19x = 126 - 50\\
\Rightarrow 19x = 76\\
\Rightarrow x = 4\\
Vậy\,x = 4\\
b){\left( {7x - 11} \right)^3} = {\left( { - 3} \right)^2}.15 + 208\\
\Rightarrow {\left( {7x - 11} \right)^3} = 9.15 + 208\\
\Rightarrow {\left( {7x - 11} \right)^3} = 135 + 208\\
\Rightarrow {\left( {7x - 11} \right)^3} = 343 = {7^3}\\
\Rightarrow 7x - 11 = 7\\
\Rightarrow 7x = 7 + 11 = 18\\
\Rightarrow x = \frac{{18}}{7}\\
c)\left| {2x - 7} \right| = 20 + 5.\left( { - 3} \right)\\
\Rightarrow \left| {2x - 7} \right| = 20 - 15 = 5\\
\Rightarrow \left[ \begin{array}{l}
2x - 7 = 5\\
2x - 7 = - 5
\end{array} \right.\\
\Rightarrow \left[ \begin{array}{l}
2x = 5 + 7 = 12\\
2x = - 5 + 7 = 2
\end{array} \right.\\
\Rightarrow \left[ \begin{array}{l}
x = 6\\
x = 1
\end{array} \right.\\
d)2016:\left[ {25 - \left( {3x + 2} \right)} \right] = {\left( { - 3} \right)^2}.7\\
\Rightarrow 2016:\left[ {25 - \left( {3x + 2} \right)} \right] = 9.7 = 63\\
\Rightarrow 25 - 3x - 2 = 2016:63\\
\Rightarrow 23 - 3x = 32\\
\Rightarrow 3x = 23 - 32\\
\Rightarrow 3x = - 9\\
\Rightarrow x = - 9:3 = - 3\\
Vậy\,x = - 3
\end{array}$
