Question

4. Determine as raízes reais das equações incompletas:

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Answer 1

Resposta:

a) 2x² - 162 = 0

2x² = 162

x² = 162 ÷ 2

x² = 81

x=9

Raízes reais de a) 2x² - 162 = 0 : 9

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b) x²-4= 0

x² = 4

x = √4

x = 2

Raízes reais de b) x²-4= 0: 2

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c) 2x² + 8x = 0

a: 2

b: 8

c: 0

∆ = b² - 4ac

∆ = 8² - 4*2*0

∆ = 64 - 0

∆ = 64

$x1 = \frac{ - b + \sqrt{64} }{2 \times 2}$

$x1 = \frac{ - 8 + 8}{4}$

$x1 = \frac{0}{4}$

x1= 0

$x2 = \frac{ - b - \sqrt{64} }{2 \times 2} \\ x2 = \frac{ - 8 - 8}{4} \\ x2 = \frac{ - 16}{4}$

x2= -4

Raízes reais de c) 2x² + 8x : 0 e -4

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d) x² - 12x

a: 1

b: -12

c: 0

∆ = b² - 4ac

∆ = (-12)² - 4*1*0

∆ = 144 - 0

∆ = 144

$x1 = \frac{ - ( - 12)+ \sqrt{144} }{2 \times 1} \\ x1 = \frac{ 12 + 12}{2} \\ x1 = \frac{24}{2}$

x1=12

$x2 = \frac{ - ( - 12) - \sqrt{144} }{2 \times 1 } \\ x2 = \frac{12 - 12}{2} \\ x2 = \frac{0}{2}$

x2=0

As raízes de d) x² - 12x : 12 e 0