A² - 18a + 17 = 0
D = b² - 4ac = 324 - 4 × 17 = 324 - 68 = 256 = 16²
x1 = ( 18 + 16) / 2 = 17
x2 = ( 18 - 16) / 2 = 1
Разложим по формуле:
a(x - x1)(x - x2)
( x - 17)( x - 1)
- 1/8x² - 3/4x + 5 = 0 (сократим на - 1/8)
x² + 6x - 40 = 0
D = b² - 4ac = 36 - 4 × 40 = 36 + 160 = 196 = 14²
x1 = ( - 6 + 14) / 2 = 4
x2 = ( - 6 - 14) / 2 = - 10
( x - 4)(x + 10)