Đáp án + Giải thích các bước giải:
`B = \frac{2x-9}{x² - 5x + 6} + \frac{x+3}{x-2} - \frac{2x + 4}{3-x}`
`= \frac{2x-9}{(x-2)(x-3)} + \frac{(x+3)(x-3)}{(x-2)(x-3) + \frac{(2x+4)(x-2)}{(x-3)(x-2)}`
`= \frac{2x - 9 + x² - 9 + 2x² - 8}{(x-3)(x-2)}`
`= \frac{3x² + 2x - 26}{(x-3)(x-2)}`
C) B = 1
`\frac{3x² + 2x - 26}{(x-3)(x-2)} = 1`
`3x² + 2x - 26 = x² - 5x + 6`
`2x² + 7x - 32 = 0`
`x² + \frac{7}{2}x - 16 = 0`
`x² + 2.x.\frac{7}{4} + (\frac{7}{4})² - \frac{306}{16} = 0`
`(x + \frac{7}{4})² = \frac{306}{16}`
\(\left[ \begin{array}{l}x=\dfrac{-7+\sqrt{305}}{4}\\x=\dfrac{-7-\sqrt{305}}{4}\end{array} \right.\)
