Question

Achar as raízes das equações :

Answer 1

a) x²-x-20=0
∆=b²-4ac
∆=(-1)²-4×1×(-20)
∆=1+80
∆=81

x=-b+-√∆/2a
x=-(-1)+-√81/2×1
x=1+-9/2

x1=1+9/2
x1=10/2
x1=5

x2=1-9/2
x2=-8/2
x2=-4

x1=5 e x2=-4

b)x²-3x-4=0
∆=b²-4ac
∆=(-3)²-4×1×(-4)
∆=9+16
∆=25

x=-b+-√∆/2a
x=-(-3)+-√25/2×1
x=3+-5/2

x1=3+5/2
x1=8/2
x1=4

x2=3-5/2
x2=-2/2
x2=-1

x1=4 e x2=-1

Answer 2

Olá

a) x² - x - 20 = 0

Coeficientes:

a = 1

b = - 1

c = - 20

Calculando delta

Δ = b² - 4.a.c

Δ = - 1² - 4.1. -20

Δ = 1 + 80

Δ = 81

Há 2 raízes reais

Aplicando Bhaskara

x = - b +- √Δ/2.a

x' = - (- 1 + √81)/2.1

x' = 1 + 9/2

x' = 10/2

x' = 5

x" = - ( 1 - √81)/2.1

x" = 1 - 9/2

x" = - 8/2

x" = - 4

S = {x' = 5 e x" = - 4}

b) x² - 3x - 4 = 0

Coeficientes:

a = 1

b = - 3

c = - 4

Calculando delta

Δ = b² - 4.a.c

Δ = - 3² - 4. 1 . - 4

Δ = 9 + 16

Δ = 25

Há 2 raízes reais

Aplicando Bhaskara

x = - b +-Δ/2.a

x' = - ( - 3 + √25)/2.1

x' = 3 + 5/2

x' = 8/2

x' = 4

x" = - ( - 3 - √25)/2.1

x" = 3 - 5/2

x" = - 2/2

x" = - 1

S = {x' = 4 e x" = - 1}

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