Question

Alguém me ajuda é pra hoje isso


a) x² - 2x - 8 =0
b) x² - 10x + 16= 0
c) x² – 2x + 16 = 0

d) 2x2 - 3x - 5 = 0
e) 9x² - 12x + 4 = 0

Answer 1

Resposta:

$x^2 - 2x - 8 =0= \\x=4\\\\\:x=-2\\\\\\\\x^2 - 10x + 16= 0=\\x=8\\\\\:x=2\\\\x^2- 2x + 16 = 0=\\\\x=1+\sqrt{15}i\\\\\:x=1-\sqrt{15}i\\\\\\\\2x2-3x-5=0\\\\x=5\\\\\\\\9x^2- 12x + 4 = 0\\\\x=\frac{2}{3}$

Answer 2

Resposta:

Explicação passo a passo:

a) x² - 2x - 8 =0

a = 1; b = -2; c = - 8

∆= b² - 4ac

∆= (-2)² - 4.1.(-8)

∆= 4+32

∆= 36

X = [ -(-2)+/- √36]/2.1

X = (2+/- 6)/2

X '= (2+6)/2= 8/2= 4

X " = (2-6)/2= -4/2= -2

R.: {4; -2}

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b) x² - 10x + 16= 0

A = 1; b = -10; c = 16

∆= b² - 4ac

∆= (-10)² - 4.1.16

∆= 100-64

∆= 36

X = [-(-10)+/- √36]/2.1

X = (10 +/- 6)/2

X' = (10+6)/2=16/2=8

X" = (10-6)/2= 4/2= 2

R.: {2;8}

_______________

c) x² – 2x + 16 = 0

a= 1; b = -2; c= 16

∆= b² - 4ac

∆= (-2)² - 4.1.16

∆= 4-64

∆= - 60

Não há solução para os Números Reais (∆<0)

__________________

d) 2x² - 3x - 5 = 0

a= 2; b = - 3; c= -5

∆= b² - 4ac

∆= (-3)² - 4.2.(-5)

∆= 9 + 8.5

∆= 49

X = (-b +/- √∆]/2a

x= [-(-3)+/- √49)]/2.2

X = (3+/-7)/4

X ' = (3+7)/4= 10/4 (:2)/(:2) = 5/2

X " = (3-7)/4= -4/4= - 1

R.: {-1; 5/2}

_________________

e) 9x² - 12x + 4 = 0

a = 9; b = - 12; c = 4

∆= b² - 4ac

∆= (-12)² - 4.9.4

∆= 144-144

∆ = 0

X= - b/2a= - (-12)/2.9= 12/18(:6)/(:6)

X = 2/3

R.: {2/3}