Question

Resolva as equações de 2 grau:A)3x²-3=2(x+1)
B) x(x+11)+2(x+21)=0
C) 6(x²-1)-x=14+5x²
(a prof falou que fecha)

Answer 1

A) 3x² - 3 = 2(x + 1)

3x² - 3 = 2x + 2
3x² - 2x - 3 - 2
3x² - 2x - 5 = 0


delta = (-2)² - 4.3.(-5)
delta = 4 + 60
delta = 64


x = -(-2) ± √64/2.3

x = 2 ± 8/6

x = 2 - 8/6 = -6/6 = -1

x = 2 + 8/6 = 10/6 = 5/3


s={ -1, 5/3 }
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B) x (x + 11) + 2(x + 21) = 0

x² + 11x + 2x + 42 = 0
x² + 13x + 42 = 0


delta = 13² - 4.1.42
delta = 169 - 168
delta = 1


x = -13 ± √1/2.1

x = -13 ± 1/2

x = -13 + 1/2 = -12/2 = -6

x = -13 - 1/2 = -14/2 = -7


s={ -6, -7 }
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c) 6(x² - 1) - x = 14 + 5x²

6x² - 6 - x = 14 + 5x²
6x² - 5x² - x - 6 - 14
x² - x - 20 = 0


delta = (-1)² - 4.1.(-20)
delta = 1 + 80
delta = 81


x = -(-1) ± √81/2.1

x = 1 ± 9/2

x = 1 - 9/2 = -8/2 = -4

x = 1 + 9/2 = 10/2 = 5


s={ -4, 5 }




☆Espero ter ajudado! tmj