Đáp án:
Giải thích các bước giải:
$\begin{array}{l}
a,2.\left( { - 2} \right) + k = - 2 - 1 \to k = - 3 + 4 = 1\\
\to k = 1\\
c,2\left( {2.1 + 1} \right) + 18 = 3\left( {1 + 2} \right)\left( {2.1 + k} \right)\\
\to 24 = 18 + 9k \to k = \frac{2}{3}\\
d.5\left( {k + 3.2} \right)\left( {2 + 1} \right) - 4\left( {1 + 2.2} \right) = 80\\
\to 15k + 90 - 20 = 80\\
\to k = \frac{2}{3}
\end{array}$
$\begin{array}{l}
b,\left( {2.\left( { - 2} \right) + 1} \right)\left( {9.\left( { - 2} \right) + 2k} \right) - 5\left( { - 2 + 2} \right) = 40\\
\to - 3\left( { - 18 + 2k} \right) = 40\\
\to - 6k + 54 = 40\\
\to k = \frac{7}{3}
\end{array}$