• Исходное уравнение:
x² - 4x - 21 = 0
(a = 1, b = -4, c = -21)
D = b² - 4ac = (-4)²- 4*1*(-21) = 16 + 84 = 100 = 10²
x₁ = (-b + √D)/2a = (4 + 10)/2 = 7
x₂ = (-b - √D)/2a = (4 - 10)/2 = - 3
ответ: x₁ = 7, x₂ = -3
x²-4x-21=0
a=1, b=-4, c=-21
D=b²-4ac=(-4)²-4×1×(-21)=16+84=100=10²
x½=-b±√D/2a=4±10/2=7 и -3
х=7; -3
• Исходное уравнение:
x² - 4x - 21 = 0
(a = 1, b = -4, c = -21)
D = b² - 4ac = (-4)²- 4*1*(-21) = 16 + 84 = 100 = 10²
x₁ = (-b + √D)/2a = (4 + 10)/2 = 7
x₂ = (-b - √D)/2a = (4 - 10)/2 = - 3
ответ: x₁ = 7, x₂ = -3
x²-4x-21=0
a=1, b=-4, c=-21
D=b²-4ac=(-4)²-4×1×(-21)=16+84=100=10²
x½=-b±√D/2a=4±10/2=7 и -3
х=7; -3