Найдите корни трехчлена. 1) 12 х^2-4 х-5.2) 5 х^2+9 х-2.3) 4 х^2-64

1) 12x² - 4x - 5 = 0

a = 12, b = - 4, c = - 5,

D = b² - 4ac = ( - 4) ² - 4 * 12 * ( - 5) = 16 + 240 = 256 > 0 - 2 действительных корня,

x₁ = ( - b + √D) / 2a = (4 + 16) / 24 = 5/6,

x₂ = ( - b - √D) / 2a = (4 - 16) / 24 = - 1/2.

2) 5x² + 9x - 2 = 0

a = 5, b = 9, c = - 2,

D = b² - 4ac = 9² - 4 * 5 * ( - 2) = 81 + 40 = 121 > 0 - 2 действительных корня,

x₁ = ( - b + √D) / 2a = ( - 9 + 11) / 10 = 1/5,

x₂ = ( - b - √D) / 2a = ( - 9 - 11) / 10 = - 2.

3) 4 х² - 64 = 0,

4 х² = 64,

х² = 64 : 4,

х² = 16,

x₁ = 4;

x₂ = - 4.