Question

Resolva as equações do 1 grau e do 2 grau a baixo
a) x+5.(x-4)-3.(x-2)=-7
B) 2x²-5x=-x
C)x²+30x+225=0

Answer 1

a) x + 5 . (x - 4) - 3 . (x - 2) = - 7

x + 5x - 20 - 3x + 6 = - 7

x + 5x - 3x - 20 + 6 + 7

x + 2x - 20 + 13

3x - 7 = 0

3x = 0 + 7

3x = 7

x = 7

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3

b) 2x² - 5x = - x

2x² - 5x + x

2x² - 4x = 0

2x(x - 4) = 0

2x = 0

x = 0

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2

x = 0

x - 4 = 0

x = 0 + 4

x = 4

c) x² + 30x + 225 = 0

∆ = b² - 4 . a . c

∆ = 30² - 4 . 1. 225

∆ = 900 - 900

∆ = 0

x = - b ± √∆

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2a

x = - 30 - 0

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2 . 1

x = - 30

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2

x = - 15