Cho \( A = \frac{{4x + 3}}{...

B

- Hướng dẫn giải

Để A=B thì:

\(\begin{array}{*{20}{l}} {\frac{{4x + 3}}{5} - \frac{{6x - 2}}{7} = \frac{{5x + 4}}{3} + 3}\\ { \Leftrightarrow \frac{{21\left( {4x + 3} \right) - 15\left( {6x - 2} \right)}}{{105}} = \frac{{35\left( {5x + 4} \right) + 3.105}}{{105}}}\\ { \Leftrightarrow \frac{{84x + 63 - 90x + 30}}{{105}} = \frac{{175x + 455}}{{105}}}\\ { \Leftrightarrow 84x + 63 - 90x + 30 = 175x + 455}\\ { \Leftrightarrow 84x - 90x - 175x = 455 - 30 - 63}\\ { \Leftrightarrow - 181x = 362}\\ { \Leftrightarrow x = - 2} \end{array}\)

Vậy để A=B thì x=−2