Question

Determine as raízes reais das equações:
a) x² - 25 = 0
b) x² -2x = 0
c) 2x² - 200 = 0
d) 4x² - 16 = 0
e) x² + 25x = 0
f) x² + 100x = 0

Answer 1

a) x² - 25 = 0

x² = 25
x = √√25
x = +/- 5

R.: x = 5 e x = - 5
¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨

b)
x² - 2x = 0
x.(x - 2) = 0
x = 0

x - 2 = 0
x = 2

R.: x = 0 e x = 2
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c)

2x² - 200 = 0
2x² = 200
x² = 200/2
x² = 100
x = √100
x = +/- 10

R.: x = 10 e x =  - 10
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d)
4x² - 16 = 0
4x² = 16
x² = 16/4
x² = 4
x = √4
x = +/- 2

R.: x = 2 e x = - 2

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e)
x² + 25x = 0

x.(x + 25) = 0
x = 0

x + 25 = 0
x = - 25

R.: x = 0 e x = - 25

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f)
x² + 100x = 0
x.(x + 100) = 0
x = 0

x + 100 = 0
x = - 100

R.: x = 0 e x = - 100
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