Question

Me ajudem nas equações

x²-4x=5

(x+1)(x-2)=-7x-10

Answer 1

x² - 4x = 5
x² - 4x - 5 = 0

Δ = b² - 4ac
Δ = (- 4)² - 4.1.(- 5)
Δ = 16 + 20
Δ = 36

x = - b ± √Δ/ 2.a
x = - (- 4) ± √36/ 2.1
x = 4 ± 6/ 2

x¹ = 4 + 6/ 2
x¹ = 10/ 2
x¹ = 5

x² = 4 - 6/ 2
x² = - 2/ 2
x² = - 1

S = {- 1, 5}

(x + 1)(x - 2) = - 7x - 10
x² - 2x + x - 2 = - 7x - 10
x² - x + 7x - 2 + 10 = 0
x² + 6x + 8 = 0

Δ = b² - 4ac
Δ = 6² - 4.1.8
Δ = 36 - 32
Δ = 4

x = - b ± √Δ/ 2a
x = - (+ 6) ±  √4/ 2.1
x = - 6 ±  2/ 2

x¹ = - 6 + 2/ 2
x¹ = - 4/ 2
x¹ = - 2

x² = - 6 - 2/ 2
x² = - 8/ 2
x² = - 4

S = {- 4, - 2}