Question

3) usando a fórmula resolutiva (Bhaskara) resolva as equações a
seguir:
a) x2 -2x -15 = 0
b) x2 - 4x +3 = 0
c) x2 + 8x + 7 = 0​

Answer 1

x = [-b±√(b²-4ac)]/2a

x = x₁,x₂

a) x² - 2x - 15 = 0

x = [-(-2)±√((-2)²-4(1)(-15))]/2(1)

x = [2±√(4+60)]/2

x = [2±√(64)]/2

x = (2±8)/2

x₁ = (2+8)/2

x₁ = 5

x₂ = (2-8)/2

x₂ = -3

b) x² - 4x + 3 = 0

x = [-(-4)±√((-4)²-4(1)(3))]/2(1)

x = [4±√(16-12)]/2

x = [4±√(4)]/2

x = (4±2)/2

x₁ = (4+2)/2

x₁ = 3

x₂ = (4-2)/2

x₂ = 1

c) x² + 8x + 7 = 0​

x = [-(8)±√((8)²-4(1)(7))]/2(1)

x = [-8±√(64-28)]/2

x = [-8±√(36)]/2

x = (-8±6)/2

x₁ = (-8+6)/2

x₁ = -1

x₂ = (-8-6)/2

x₂ = -7