Đáp án:
Giải thích các bước giải:
\(\begin{array}{l}
1.5x - 5 + 7x = 2\\
\to 12x = 7 \to x = \frac{7}{{12}}\\
2.3\left( {{x^2} - 4x + 4} \right) + 4x - 12 = 3{x^2} + 3x - 9\\
\to - 12x + 12 + 4x - 12 = 3x - 9\\
\to - 11x = - 9 \to x = \frac{9}{{11}}\\
3.{x^2} + 6x + 9 + {x^2} - 4x + 4 = 2{x^2} - 4x + 2\\
\to 6x = - 11 \to x = \frac{{ - 11}}{6}\\
4.2{x^2} + 9x - 5 + 4x - 12 = 2{x^2} + 2\\
\to 13x = 19 \to x = \frac{{19}}{{13}}\\
5.10 - 3x + 6 = 2x + 6 - 5\\
\to 5x = 15 \to x = 3\\
6.2{x^2} - x - 2{x^2} = 5x - 15\\
\to 6x = 15 \to x = \frac{{15}}{6}
\end{array}\)
