Tìm x biết: (x - 5)(x - 4) - (x + 1)(x - 2) = 7
Tìm x biết: (x – 5)(x – 4) – (x + 1)(x – 2) = 7.
(x – 5)(x – 4) – (x + 1)(x – 2) = 7
⇔ x2 – 9x + 20 – (x2 – x – 2) = 7
⇔ −8x + 22 = 7
⇔ 8x = 15\[ \Leftrightarrow x = \frac{{15}}{8}\]
Vậy \(x = \frac{{15}}{8}\).