Đáp án:
\(\left[ \begin{array}{l}
x = - \dfrac{1}{3}\\
x = \dfrac{{11}}{7}
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
\dfrac{{\left( {3x + 1} \right)\left( {3x - 2} \right)}}{3} + \dfrac{{5\left( {3x + 1} \right)}}{1} = \dfrac{{2\left( {2x + 1} \right)\left( {3x + 1} \right)}}{3} + 2x\left( {3x + 1} \right)\\
\to 9{x^2} - 3x - 2 + 15\left( {3x + 1} \right) = 2\left( {6{x^2} + 5x + 1} \right) + 6x\left( {3x + 1} \right)\\
\to 9{x^2} - 3x - 2 + 45x + 15 = 12{x^2} + 10x + 2 + 18{x^2} + 6x\\
\to 21{x^2} - 26x - 11 = 0\\
\to 21{x^2} + 7x - 33x - 11 = 0\\
\to 7x\left( {3x + 1} \right) - 11\left( {3x + 1} \right) = 0\\
\to \left( {3x + 1} \right)\left( {7x - 11} \right) = 0\\
\to \left[ \begin{array}{l}
x = - \dfrac{1}{3}\\
x = \dfrac{{11}}{7}
\end{array} \right.
\end{array}\)
