Giair phương trình sau:
1. (x - 3) (x + 4) = (2 - x) (1 - x)
2. \(\frac{2x}{15}\) - \(\frac{15-2x}{10}\) = \(\frac{7}{6}\)
3. \(\frac{x}{15}\) + \(\frac{x+1}{16}\) + \(\frac{x+2}{17}\) + \(\frac{x+3}{18}\) + \(\frac{x+4}{19}\) = 5
4. \(\frac{x+1}{11}\) + \(\frac{2x-5}{15}\) = \(\frac{3x-47}{17}\) - \(\frac{4x-59}{19}\)
5. x2 + 9x + 20 = 0
6. x3 + 2x - 3 = 0