Question

Encontre as raízes das equações de 2 grau A: x²-x-20 =0


B : x²-3x-4=0​

Answer 1

Resposta:

x² - x - 20 = 0 

a= 1

b= -1

c= -20

Δ = b² - 4. a . c

Δ= (-1)² - 4. 1. (-20)

Δ= 1 +80

Δ= 81

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

(5,-4)

x² - 3x - 4 = 0

a=1

b= -3

c= -4

Δ = b² - 4. a . c

Δ= (-3)² - 4. 1. (-4)

Δ= 9 + 16

Δ= 25

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

(4,-1)