( x - 2,5)² = 49
( x - 2,5)( x - 2,5) = 49
x² - 5x + 6,25 = 49
x² + 5x - 49 + 6,25 = 0
x² + 5x - 42,75 =0
D = b² - 4ac = 5² - 4 × 1 × ( - 42,75) = 25 + 171 = 196 = 14²
x₁ = - 5 + 14 / 2 = 9/2 = 4,5
x₂ = - 5 - 14 / 2 = - 19 / 2 = -9,5
Ответ: x₁ = 4,5, x₂ = - 9,5