\(\dfrac{1}{{x - 1}} + \dfrac{2}{{x - 2}} + \dfrac{3}{{x - 3}} = \dfrac{6}{{x - 6}}\)
ĐKXĐ: \(x \ne1; x \ne 2;x \ne 3;x \ne6\)
\( \Leftrightarrow \dfrac{{2\left( {x - 3} \right) + 3\left( {x - 2} \right)}}{{\left( {x - 2} \right)\left( {x - 3} \right)}} = \dfrac{{6\left( {x + 1} \right) - \left( {x - 6} \right)}}{{\left( {x - 6} \right)\left( {x - 1} \right)}}\\ \Leftrightarrow \dfrac{{5x - 12}}{{\left( {x - 2} \right)\left( {x - 3} \right)}} = \dfrac{{5x}}{{\left( {x - 6} \right)\left( {x - 1} \right)}}\\ \Leftrightarrow \left( {5x - 12} \right)\left( {{x^2} - 7x + 16} \right) = 5x\left( {{x^2} - 5x + 6} \right)\\ \Leftrightarrow - 22{x^2} + 84x - 72 = 0\\ \Leftrightarrow \left[ \begin{array}{l} x = \dfrac{{21 + 3\sqrt 5 }}{{11}} (tm)\\ x = \dfrac{{21 - 3\sqrt 5 }}{{11}} (tm) \end{array} \right. \)
