Question

Resolva pfavor :
A. x² +x= 0
B. 3x²+7x=0
C. 5x²-x=0
D. -3x²+15x=0

Answer 1

a) x^2+x=0
delta=b^2-4ac
delta=1^2-4.1.0
delta=1-0
delta=1
x=-b-/+ raiz de delta/2a
x=-1-1/2.1
x=-2/2
x=-1
x=-1+1/2.1
x=0/2
x=0
b) 3x^2+7x=0
delta=b^2-4ac
delta=7^2-4.3.0
delta=49-0
delta=49
x=-b-/+ raiz de delta/2a
x=-7-7/2.3
x=-14/6 (:2)
x=-7/3
x=-7+7/2.3
x=0/6
x=0
c) 5x^2-x=0
delta=b^2-4ac
delta=(-1)^2-4.5.0
delta=1-0
delta=1
x=-b-/+ raiz de delta/2a
x=-(-1)-1/2.5
x=1-1/10
x=0/10
x=0
x=-(-1)+1/2.5
x=1+1/10
x=2/10
x=0,2
d) -3x^2+15x=0
delta=b^2-4ac
delta=15^2-4.(-3).0
delta=225+0
delta=225
x=-b-/+ raiz de delta/2a
x=-15-15/2.(-3)
x=-30/-6
x=5
x=-15+15/2.(-3)
x=0/-6
x=0

Answer 2

Equação de segundo grau:

ax² + bx + c = 0

Δ = b² - 4.a.c

x = (-b +-√Δ) / 2.a

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a) x² + x = 0

a = 1
b = 1
c = 0

Δ = 1² - 4.1.0 
Δ = 1 - 0
Δ = 1

x = (-1 +-√1) / 2.1
x = (-1 +- 1) / 2

x' = (-1 + 1) / 2 = 0/2 = 0
x" = (-1 -1) / 2 = -2/2 = -1

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b) 3x² + 7x = 0

a = 3
b = 7
c = 0

Δ = 7² - 4.3.0
Δ = 49 - 0
Δ = 49

x = (-7 +-√49) / 2.3
x = (-7 +- 7) / 6

x' = (-7 + 7) / 6 = 0/6 = 0
x" = (-7 - 7) / 6 = -14/6 = -7/3

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c) 5x² - x = 0

a = 5
b = -1
c = 0

Δ = (-1)² - 4.5.0
Δ = 1 - 0
Δ = 1

x = (-(-1) +-√1) / 2.5
x = (1 +- 1) / 10

x' = (1 + 1) / 10 = 2/10 = 1/5
x" = (1 - 1) / 10 = 0/10 = 0

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d) -3x² + 15x = 0

a = -3
b = 15
c = 0

Δ = 15² - 4.(-3).0
Δ = 225 - 0
Δ = 225

x = (-15 +-√225) / 2.(-3)
x = (-15 +- 15) / -6

x' = (-15 + 15) / -6 = 0/-6 = 0
x" = (-15 - 15) / -6 = -30/-6 = 5

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Espero ter ajudado (: