tim x 2 81 )*( x 5 2 )= 0

(x + 5)² - (x - 5)² - 2x + 1 = 0

⇔ x² + 10x + 25 – (x² – 10x + 25) – 2x + 1 = 0

⇔ x² + 10x + 25 – x² + 10x – 25 – 2x + 1 = 0

⇔ 20x – 2x + 1 = 0

⇔ 18x + 1 = 0

⇔ \(x = - \frac{1}{{18}}\)

Vậy \(x = - \frac{1}{{18}}\)