Giải thích các bước giải:
\(\begin{array}{l}
1,25x + 10 - 80x + 10 = 24x + 12 - 150\\
\to 79x = 158\\
\to x = 2\\
2,9x + 6 - 3x - 1 = 12x + 10\\
\to 6x = - 5\\
\to x = - \frac{5}{6}\\
3,8 - 24x - 4 - 6x = 140 - 30x - 15\\
\to 0x = 121\left( {voli} \right)
\end{array}\)
⇒ Vô nghiệm
\(\begin{array}{l}
4,21.\left( {9x - 0,7} \right) - 12\left( {5x - 1,5} \right) = 28\left( {7x - 1,1} \right) - 70\left( {0,4 - 2x} \right)\\
\to 189x - \frac{{147}}{{10}} - 60x + 18 = 196x - \frac{{154}}{5} - 28 + 140x\\
\to 207x = \frac{{621}}{{10}}\\
\to x = \frac{3}{{10}}\\
5,4\left( {{x^2} + 4x - 5} \right) - {x^2} - 7x - 10 = 3\left( {{x^2} + x - 2} \right)\\
\to 16x - 20 - 7x - 10 = 3x - 6\\
\to 6x = 24 \to x = 4\\
6,\left( {5x - 3} \right)\left( {\frac{{12x - 3 - 10x - 5}}{{15}}} \right) = 0\\
\to \left[ \begin{array}{l}
x = \frac{3}{5}\\
2x - 8 = 0
\end{array} \right. \to \left[ \begin{array}{l}
x = \frac{3}{5}\\
x = 4
\end{array} \right.
\end{array}\)
