найдите корни уравнения x^2+x=12; x^2-7x=8; x^2+7=8x

1) x² + x = 12,

x² + x - 12 = 0,

a = 1, b = 1, c = - 12,

D = b² - 4ac = 1² - 4 * 1 * ( - 12) = 49 > 0 - 2 корня,

x₁ = ( - b + √D) / 2a = ( - 1 + 7) / 2 = 3,

x₂ = ( - b - √D) / 2a = ( - 1 - 7) / 2 = - 4.

2) x² - 7x = 8,

x² - 7x - 8 = 0,

a = 1, b = - 7, c = - 8,

D = ( - 7) ² - 4 * 1 * ( - 8) = 81 > 0 - 2 корня,

x₁ = (7 + 9) / 2 = 8,

x₂ = (7 - 9) / 2 = - 1.

3) x² + 7 = 8x,

x² - 8x + 7 = 0,

a = 1, b = - 8, c = 7,

D = ( - 8) ² - 4 * 1 * 7 = 36 > 0 - 2 корня,

x₁ = (8 + 6) / 2 = 7,

x₂ = (8 - 6) / 2 = 1.